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Constant-Q transform

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103: 1582: 1233: 55: 81:, from low (left) to high (right). The y-axis is time, starting from pressing the piano chord at the bottom, and releasing the piano chord at the top, 8 seconds later. Darker pixels correspond to higher values of the Constant-Q transform. The peaks correspond closely to the precise frequencies of the vibrating piano strings. Thus the peaks can be used to detect the notes played on the piano. The lowest 3 peaks are the 1680:"When the mother wavelet can be interpreted as a windowed sinusoid (such as the Morlet wavelet), the wavelet transform can be interpreted as a constant-Q Fourier transform. Before the theory of wavelets, constant-Q Fourier transforms (such as obtained from a classic third-octave filter bank) were not easy to invert, because the basis signals were not orthogonal." 1630:
At the bottom of the piano scale (about 30 Hz), a difference of 1 semitone is a difference of approximately 1.5 Hz, whereas at the top of the musical scale (about 5 kHz), a difference of 1 semitone is a difference of approximately 200 Hz. So for musical data the exponential frequency resolution of constant-Q transform is ideal.
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The transform exhibits a reduction in frequency resolution with higher frequency bins, which is desirable for auditory applications. The transform mirrors the human auditory system, whereby at lower-frequencies spectral resolution is better, whereas temporal resolution improves at higher frequencies.
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In general, the transform is well suited to musical data, and this can be seen in some of its advantages compared to the fast Fourier transform. As the output of the transform is effectively amplitude/phase against log frequency, fewer frequency bins are required to cover a given range effectively,
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A development on this method with improved invertibility involves performing CQT (via fast Fourier transform) octave-by-octave, using lowpass filtered and downsampled results for consecutively lower pitches. Implementations of this method include the MATLAB implementation and LibROSA's Python
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In addition, the harmonics of musical notes form a pattern characteristic of the timbre of the instrument in this transform. Assuming the same relative strengths of each harmonic, as the fundamental frequency changes, the relative position of these harmonics remains constant. This can make
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Also note that because the frequency scale is logarithmic, there is no true zero-frequency / DC term present, which may be a drawback in applications that are interested in the DC term. Although for applications that are not interested in the DC such as audio, this is not a drawback.
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Relative to the Fourier transform, implementation of this transform is more tricky. This is due to the varying number of samples used in the calculation of each frequency bin, which also affects the length of any windowing function implemented.
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Alternatively, the constant-Q transform can be approximated by using multiple fast Fourier transforms of different window sizes and/or sampling rate at different frequency ranges then stitch it together. This is called multiresolution
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and this proves useful where frequencies span several octaves. As the range of human hearing covers approximately ten octaves from 20 Hz to around 20 kHz, this reduction in output data is significant.
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implementation. LibROSA combines the subsampled method with the direct fast Fourier transform method (which it dubs "pseudo-CQT") by having the latter process higher frequencies as a whole.
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The variable-Q transform is the same as constant-Q transform, but the only difference is the filter Q is variable, hence the name variable-Q transform. The variable-Q transform is useful
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can be used for faster calculation of constant-Q transform, since the sliding discrete Fourier transform does not have to be linear-frequency spacing and same window size per bin.
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identification of instruments much easier. The constant Q transform can also be used for automatic recognition of musical keys based on accumulated chroma content.
89:, which correspond to the remaining smaller peaks to the right of the fundamental pitches. The overtones are smaller in intensity than the fundamental pitch. 1887: 580: 1057: 1422:
This formula can be modified to have extra parameters to adjust sharpness of the transition between constant-Q and constant-bandwidth like this:
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The relative power of each bin will decrease at higher frequencies, as these sum over fewer terms. To compensate for this, we normalize by
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Any windowing function will be a function of window length, and likewise a function of window number. For example, the equivalent
1269: 1250: 1276: 1932: 325: 717: 1563: 1574:, however the window sizes for multiresolution fast Fourier transforms are different per-octave, rather than per-bin. 1283: 499: 1316: 953:{\displaystyle W=\alpha -(1-\alpha )\cos {\frac {2\pi n}{N-1}},\quad \alpha =25/46,\quad 0\leqslant n\leqslant N-1.} 1334: 1825:
11th International Conference on Digital Audio Effects (DAFx-08) Proceedings September 1-4th, 2008 Espoo, Finland
1778: 1265: 1254: 1722: 1597: 261:{\displaystyle \delta f_{k}=2^{1/n}\cdot \delta f_{k-1}=\left(2^{1/n}\right)^{k}\cdot \delta f_{\text{min}},} 1794: 1601: 1922: 1571: 308: 1839:"A multiresolution non-negative tensor factorization approach for single channel sound source separation" 1827:. DAFx, Espoo, Finland, pp. 363-369, Proc. of the Int. Conf. on Digital Audio Effects (DAFx-08), 1/09/08. 1677: 1004: 969: 106:
Its waveform does not visually communicate pitch information like the Constant-Q transform is able to do.
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of the C major chord (C, E, G). Each string also vibrates at multiples of the fundamental, known as
1290: 1509:{\displaystyle \delta f_{k}=\left({\frac {2}{\sqrt{f_{k}^{\alpha }+\gamma ^{\alpha }}}}\right)Q.} 1243: 82: 1551:. However, the fast Fourier transform can itself be employed, in conjunction with the use of a 1548: 1661: 471:
being the sampling period of our data, for each frequency bin we can define the following:
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This is shown below to be the integer number of cycles processed at a center frequency
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The simplest way to implement a variable-Q transform is add a bandwidth offset called
664:{\displaystyle N={\frac {f_{\text{s}}}{\delta f_{k}}}={\frac {f_{\text{s}}}{f_{k}}}Q.} 1875: 1858: 1740: 44: 20: 1793:
McFee, Brian; Battenberg, Eric; Lostanlen, Vincent; Thomé, Carl (12 December 2018).
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The equivalent transform kernel can be found by using the following substitutions:
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Audio of the C Major piano chord used to generate the Constant-Q transform above.
1691: 796: 126: 102: 48: 1916: 1862: 78: 70: 1212:{\displaystyle X={\frac {1}{N}}\sum _{n=0}^{N-1}Wxe^{\frac {-j2\pi Qn}{N}}.} 1763: 1593: 1333:. There are ways to calculate the bandwidth of the VQT, one of them using 1888:
A New Method for Tracking Modulations in Tonal Music in Audio Data Format
1692:"End-to-End Music Transcription Using Fine-Tuned Variable-Q Filterbanks" 1581: 1718: 1657: 1539:
The direct calculation of the constant-Q transform (either using naive
1257: in this section. Unsourced material may be challenged and removed. 562:. As such, this somewhat defines the time complexity of the transform. 1739:
FitzGerald, Derry; Cychowski, Marcin T.; Cranitch, Matt (1 May 2006).
1412:{\displaystyle \delta f_{k}=\left({\frac {2}{f_{k}+\gamma }}\right)Q.} 86: 74: 1723:
An efficient algorithm for the calculation of a constant Q transform
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is the number of integer cycles processed at this central frequency.
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The window length of each bin is now a function of the bin number:
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International Joint Conference on Neural Network (IJCNN’00).
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transform. Its design is suited for musical representation.
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is the number of samples processed per cycle at frequency
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Hendrik Purwins, Benjamin Blankertz and Klaus Obermayer,
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The transform can be thought of as a series of filters
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where time resolution on low frequencies is important
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Short-time Fourier transform with variable resolution
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equal to a multiple of the previous filter's width:
1531:frequency scale, in terms of frequency resolution. 1222: 775:{\displaystyle N=N=Q{\frac {f_{\text{s}}}{f_{k}}}.} 291:is the central frequency of the lowest filter, and 1876:http://newt.phys.unsw.edu.au/jw/graphics/notes.GIF 1761: 1523:as a parameter for transition sharpness and where 1508: 1411: 1211: 1039: 993: 952: 774: 663: 543: 445: 260: 1765:Constant-Q Transform Toolbox for Music Processing 1914: 544:{\displaystyle Q={\frac {f_{k}}{\delta f_{k}}}.} 121:, logarithmically spaced in frequency, with the 1762:Schörkhuber, Christian; Klapuri, Anssi (2010). 1662:Calculation of a constant Q spectral transform 1819:Bradford, R, ffitch, J & Dobson, R 2008, 1788: 1786: 1836: 1051:After these modifications, we are left with 1783: 1689: 456:Given a data series at sampling frequency 1741:"Towards an Inverse Constant Q Transform" 1317:Learn how and when to remove this message 1837:Kırbız, S.; GĂĽnsel, B. (December 2014). 101: 90: 53: 47:and very closely related to the complex 1795:"librosa: core/constantq.py at 8d26423" 1915: 1897: 1592: with: nonstationary Gabor frames 1880: 1813: 1621:Comparison with the Fourier transform 1745:Audio Engineering Society Convention 1576: 1547:) is slow when compared against the 1337:as a value for VQT bin's bandwidth. 1255:adding citations to reliable sources 1226: 1751:. Paris: Audio Engineering Society. 1712: 1534: 1040:{\displaystyle {\frac {2\pi Q}{N}}} 994:{\displaystyle {\frac {2\pi k}{N}}} 13: 1651: 1564:sliding discrete Fourier transform 39:, transforms a data series to the 14: 1944: 1699:Rochester Institute of Technology 1580: 1335:equivalent rectangular bandwidth 1231: 1223:Variable-Q bandwidth calculation 1869: 1690:Cwitkowitz, Frank C.Jr (2019). 1242:needs additional citations for 919: 898: 1830: 1755: 1732: 1683: 1671: 1199: 1193: 1160: 1154: 1148: 1136: 1122: 1116: 1091: 1085: 1070: 1064: 1031: 1025: 941: 935: 883: 877: 851: 839: 827: 815: 736: 730: 593: 587: 404: 398: 392: 380: 344: 332: 315:for a frame shifted to sample 302: 1: 1645: 295:is the number of filters per 1855:10.1016/j.sigpro.2014.05.019 1678:Continuous Wavelet Transform 1572:short-time Fourier transform 309:short-time Fourier transform 7: 1933:Music information retrieval 10: 1949: 1541:discrete Fourier transform 319:is calculated as follows: 1821:Sliding with a constant-Q 1905:The Constant Q Transform 1729:, 92(5):2698–2701, 1992. 1721:and Miller S. Puckette, 280:is the bandwidth of the 966:Our digital frequency, 490:, the "quality factor": 83:fundamental frequencies 43:. It is related to the 1668:, 89(1):425–434, 1991. 1549:fast Fourier transform 1510: 1413: 1266:"variable q transform" 1213: 1132: 1041: 995: 954: 776: 665: 567:Window length for the 545: 447: 376: 262: 109: 107: 99: 1511: 1414: 1214: 1097: 1042: 996: 955: 777: 666: 546: 448: 350: 263: 105: 97: 77:, mapped to standard 57: 1903:Benjamin Blankertz, 1429: 1351: 1251:improve this article 1058: 1005: 970: 809: 718: 581: 500: 326: 144: 125:-th filter having a 59:Constant-Q transform 29:variable-Q transform 25:constant-Q transform 1923:Integral transforms 1727:J. Acoust. Soc. Am. 1666:J. Acoust. Soc. Am. 1600:). You can help by 1543:or slightly faster 1473: 19:In mathematics and 1894:, 6:270-275, 2000. 1545:Goertzel algorithm 1527:of 2 is equals to 1506: 1459: 1409: 1209: 1037: 991: 950: 772: 661: 541: 443: 258: 110: 108: 100: 31:, simply known as 1928:Harmonic analysis 1843:Signal Processing 1618: 1617: 1598:as used by Matlab 1594:as described here 1494: 1493: 1397: 1327: 1326: 1319: 1301: 1203: 1095: 1035: 989: 893: 767: 754: 653: 640: 626: 608: 536: 252: 95: 45:Fourier transform 21:signal processing 1940: 1908: 1901: 1895: 1884: 1878: 1873: 1867: 1866: 1834: 1828: 1817: 1811: 1810: 1808: 1806: 1790: 1781: 1777: 1775: 1773: 1759: 1753: 1752: 1736: 1730: 1716: 1710: 1709: 1707: 1706: 1696: 1687: 1681: 1675: 1669: 1655: 1613: 1610: 1584: 1577: 1535:Fast calculation 1515: 1513: 1512: 1507: 1499: 1495: 1492: 1487: 1486: 1485: 1472: 1467: 1457: 1453: 1444: 1443: 1418: 1416: 1415: 1410: 1402: 1398: 1396: 1389: 1388: 1375: 1366: 1365: 1332: 1322: 1315: 1311: 1308: 1302: 1300: 1259: 1235: 1227: 1218: 1216: 1215: 1210: 1205: 1204: 1202: 1188: 1168: 1131: 1111: 1096: 1094: 1077: 1046: 1044: 1043: 1038: 1036: 1034: 1020: 1009: 1000: 998: 997: 992: 990: 985: 974: 959: 957: 956: 951: 912: 894: 892: 872: 861: 781: 779: 778: 773: 768: 766: 765: 756: 755: 752: 746: 670: 668: 667: 662: 654: 652: 651: 642: 641: 638: 632: 627: 625: 624: 623: 610: 609: 606: 600: 550: 548: 547: 542: 537: 535: 534: 533: 520: 519: 510: 452: 450: 449: 444: 439: 438: 434: 375: 364: 267: 265: 264: 259: 254: 253: 250: 238: 237: 232: 228: 227: 223: 202: 201: 180: 179: 175: 159: 158: 96: 73:. The x-axis is 41:frequency domain 1948: 1947: 1943: 1942: 1941: 1939: 1938: 1937: 1913: 1912: 1911: 1902: 1898: 1885: 1881: 1874: 1870: 1835: 1831: 1818: 1814: 1804: 1802: 1791: 1784: 1771: 1769: 1760: 1756: 1737: 1733: 1719:Judith C. Brown 1717: 1713: 1704: 1702: 1694: 1688: 1684: 1676: 1672: 1658:Judith C. Brown 1656: 1652: 1648: 1623: 1614: 1608: 1605: 1590:needs expansion 1537: 1529:hyperbolic sine 1488: 1481: 1477: 1468: 1463: 1458: 1452: 1448: 1439: 1435: 1430: 1427: 1426: 1384: 1380: 1379: 1374: 1370: 1361: 1357: 1352: 1349: 1348: 1344:like this one: 1330: 1323: 1312: 1306: 1303: 1260: 1258: 1248: 1236: 1225: 1189: 1169: 1167: 1163: 1112: 1101: 1081: 1076: 1059: 1056: 1055: 1021: 1010: 1008: 1006: 1003: 1002: 975: 973: 971: 968: 967: 908: 873: 862: 860: 810: 807: 806: 761: 757: 751: 747: 745: 719: 716: 715: 694: 687: 680: 647: 643: 637: 633: 631: 619: 615: 611: 605: 601: 599: 582: 579: 578: 560: 529: 525: 521: 515: 511: 509: 501: 498: 497: 483: 462: 430: 411: 407: 365: 354: 327: 324: 323: 305: 290: 279: 249: 245: 233: 219: 215: 211: 207: 206: 191: 187: 171: 167: 163: 154: 150: 145: 142: 141: 136: 120: 91: 79:musical pitches 61:applied to the 17: 12: 11: 5: 1946: 1936: 1935: 1930: 1925: 1910: 1909: 1896: 1879: 1868: 1829: 1812: 1782: 1754: 1731: 1711: 1682: 1670: 1649: 1647: 1644: 1622: 1619: 1616: 1615: 1587: 1585: 1536: 1533: 1517: 1516: 1505: 1502: 1498: 1491: 1484: 1480: 1476: 1471: 1466: 1462: 1456: 1451: 1447: 1442: 1438: 1434: 1420: 1419: 1408: 1405: 1401: 1395: 1392: 1387: 1383: 1378: 1373: 1369: 1364: 1360: 1356: 1325: 1324: 1239: 1237: 1230: 1224: 1221: 1220: 1219: 1208: 1201: 1198: 1195: 1192: 1187: 1184: 1181: 1178: 1175: 1172: 1166: 1162: 1159: 1156: 1153: 1150: 1147: 1144: 1141: 1138: 1135: 1130: 1127: 1124: 1121: 1118: 1115: 1110: 1107: 1104: 1100: 1093: 1090: 1087: 1084: 1080: 1075: 1072: 1069: 1066: 1063: 1049: 1048: 1033: 1030: 1027: 1024: 1019: 1016: 1013: 988: 984: 981: 978: 963: 962: 961: 960: 949: 946: 943: 940: 937: 934: 931: 928: 925: 922: 918: 915: 911: 907: 904: 901: 897: 891: 888: 885: 882: 879: 876: 871: 868: 865: 859: 856: 853: 850: 847: 844: 841: 838: 835: 832: 829: 826: 823: 820: 817: 814: 801: 800: 797:Hamming window 793: 785: 784: 783: 782: 771: 764: 760: 750: 744: 741: 738: 735: 732: 729: 726: 723: 710: 709: 702: 701: 692: 685: 678: 673: 672: 671: 660: 657: 650: 646: 636: 630: 622: 618: 614: 604: 598: 595: 592: 589: 586: 573: 572: 564: 563: 558: 553: 552: 551: 540: 532: 528: 524: 518: 514: 508: 505: 492: 491: 485: 479: 475:Filter width, 460: 454: 453: 442: 437: 433: 429: 426: 423: 420: 417: 414: 410: 406: 403: 400: 397: 394: 391: 388: 385: 382: 379: 374: 371: 368: 363: 360: 357: 353: 349: 346: 343: 340: 337: 334: 331: 304: 301: 288: 275: 269: 268: 257: 248: 244: 241: 236: 231: 226: 222: 218: 214: 210: 205: 200: 197: 194: 190: 186: 183: 178: 174: 170: 166: 162: 157: 153: 149: 132: 127:spectral width 116: 49:Morlet wavelet 15: 9: 6: 4: 3: 2: 1945: 1934: 1931: 1929: 1926: 1924: 1921: 1920: 1918: 1906: 1900: 1893: 1889: 1883: 1877: 1872: 1864: 1860: 1856: 1852: 1848: 1844: 1840: 1833: 1826: 1822: 1816: 1800: 1796: 1789: 1787: 1780: 1767: 1766: 1758: 1750: 1746: 1742: 1735: 1728: 1724: 1720: 1715: 1700: 1693: 1686: 1679: 1674: 1667: 1663: 1659: 1654: 1650: 1643: 1639: 1635: 1631: 1627: 1612: 1609:December 2018 1603: 1599: 1595: 1591: 1588:This section 1586: 1583: 1579: 1578: 1575: 1573: 1567: 1565: 1560: 1556: 1554: 1550: 1546: 1542: 1532: 1530: 1526: 1522: 1503: 1500: 1496: 1489: 1482: 1478: 1474: 1469: 1464: 1460: 1454: 1449: 1445: 1440: 1436: 1432: 1425: 1424: 1423: 1406: 1403: 1399: 1393: 1390: 1385: 1381: 1376: 1371: 1367: 1362: 1358: 1354: 1347: 1346: 1345: 1343: 1338: 1336: 1321: 1318: 1310: 1299: 1296: 1292: 1289: 1285: 1282: 1278: 1275: 1271: 1268: â€“  1267: 1263: 1262:Find sources: 1256: 1252: 1246: 1245: 1240:This section 1238: 1234: 1229: 1228: 1206: 1196: 1190: 1185: 1182: 1179: 1176: 1173: 1170: 1164: 1157: 1151: 1145: 1142: 1139: 1133: 1128: 1125: 1119: 1113: 1108: 1105: 1102: 1098: 1088: 1082: 1078: 1073: 1067: 1061: 1054: 1053: 1052: 1028: 1022: 1017: 1014: 1011: 986: 982: 979: 976: 965: 964: 947: 944: 938: 932: 929: 926: 923: 920: 916: 913: 909: 905: 902: 899: 895: 889: 886: 880: 874: 869: 866: 863: 857: 854: 848: 845: 842: 836: 833: 830: 824: 821: 818: 812: 805: 804: 803: 802: 798: 794: 791: 787: 786: 769: 762: 758: 748: 742: 739: 733: 727: 724: 721: 714: 713: 712: 711: 707: 706: 705: 699: 695: 688: 681: 674: 658: 655: 648: 644: 634: 628: 620: 616: 612: 602: 596: 590: 584: 577: 576: 575: 574: 570: 566: 565: 561: 554: 538: 530: 526: 522: 516: 512: 506: 503: 496: 495: 494: 493: 489: 486: 482: 478: 474: 473: 472: 470: 466: 459: 440: 435: 431: 427: 424: 421: 418: 415: 412: 408: 401: 395: 389: 386: 383: 377: 372: 369: 366: 361: 358: 355: 351: 347: 341: 338: 335: 329: 322: 321: 320: 318: 314: 310: 300: 298: 294: 287: 283: 278: 274: 255: 246: 242: 239: 234: 229: 224: 220: 216: 212: 208: 203: 198: 195: 192: 188: 184: 181: 176: 172: 168: 164: 160: 155: 151: 147: 140: 139: 138: 135: 131: 128: 124: 119: 115: 104: 88: 84: 80: 76: 72: 68: 64: 60: 56: 52: 50: 46: 42: 38: 34: 30: 26: 22: 1899: 1891: 1882: 1871: 1846: 1842: 1832: 1824: 1815: 1803:. Retrieved 1798: 1770:. Retrieved 1764: 1757: 1748: 1744: 1734: 1726: 1714: 1703:. Retrieved 1698: 1685: 1673: 1665: 1653: 1640: 1636: 1632: 1628: 1624: 1606: 1602:adding to it 1589: 1568: 1561: 1557: 1538: 1524: 1520: 1518: 1421: 1341: 1339: 1328: 1313: 1304: 1294: 1287: 1280: 1273: 1261: 1249:Please help 1244:verification 1241: 1050: 789: 703: 697: 690: 683: 676: 568: 556: 487: 480: 476: 468: 464: 457: 455: 316: 312: 306: 292: 285: 284:-th filter, 281: 276: 272: 270: 133: 129: 122: 117: 113: 111: 58: 36: 32: 28: 24: 18: 1805:12 December 1772:12 December 1307:August 2022 303:Calculation 1917:Categories 1705:2022-08-21 1646:References 1277:newspapers 1001:, becomes 1863:0165-1684 1849:: 56–69. 1801:. librosa 1490:α 1483:α 1479:γ 1470:α 1433:δ 1394:γ 1355:δ 1180:π 1171:− 1126:− 1099:∑ 1015:π 980:π 945:− 930:⩽ 924:⩽ 900:α 887:− 867:π 858:⁡ 849:α 846:− 837:− 834:α 613:δ 523:δ 422:π 413:− 387:− 370:− 352:∑ 243:δ 240:⋅ 196:− 185:δ 182:⋅ 148:δ 87:overtones 75:frequency 799:would be 571:-th bin: 63:waveform 1907:, 1999. 1701:: 32–34 1291:scholar 67:C major 1861:  1799:GitHub 1553:kernel 1293:  1286:  1279:  1272:  1264:  675:Since 297:octave 271:where 69:piano 23:, the 1823:, in 1779:paper 1695:(PDF) 1596:(and 1519:with 1298:JSTOR 1284:books 71:chord 65:of a 1859:ISSN 1807:2018 1774:2018 1562:The 1270:news 463:= 1/ 307:The 35:and 27:and 1851:doi 1847:105 1749:120 1604:. 1253:by 855:cos 311:of 289:min 251:min 37:VQT 33:CQT 1919:: 1890:, 1857:. 1845:. 1841:. 1797:. 1785:^ 1747:. 1743:. 1725:, 1697:. 1664:, 1660:, 948:1. 914:46 906:25 696:, 477:δf 467:, 299:. 273:δf 130:δf 1865:. 1853:: 1809:. 1776:. 1708:. 1611:) 1607:( 1525:α 1521:α 1504:. 1501:Q 1497:) 1475:+ 1465:k 1461:f 1455:2 1450:( 1446:= 1441:k 1437:f 1407:. 1404:Q 1400:) 1391:+ 1386:k 1382:f 1377:2 1372:( 1368:= 1363:k 1359:f 1342:Îł 1320:) 1314:( 1309:) 1305:( 1295:· 1288:· 1281:· 1274:· 1247:. 1207:. 1200:] 1197:k 1194:[ 1191:N 1186:n 1183:Q 1177:2 1174:j 1165:e 1161:] 1158:n 1155:[ 1152:x 1149:] 1146:n 1143:, 1140:k 1137:[ 1134:W 1129:1 1123:] 1120:k 1117:[ 1114:N 1109:0 1106:= 1103:n 1092:] 1089:k 1086:[ 1083:N 1079:1 1074:= 1071:] 1068:k 1065:[ 1062:X 1047:. 1032:] 1029:k 1026:[ 1023:N 1018:Q 1012:2 987:N 983:k 977:2 942:] 939:k 936:[ 933:N 927:n 921:0 917:, 910:/ 903:= 896:, 890:1 884:] 881:k 878:[ 875:N 870:n 864:2 852:) 843:1 840:( 831:= 828:] 825:n 822:, 819:k 816:[ 813:W 792:. 790:N 770:. 763:k 759:f 753:s 749:f 743:Q 740:= 737:] 734:k 731:[ 728:N 725:= 722:N 698:Q 693:k 691:f 686:k 684:f 682:/ 679:s 677:f 659:. 656:Q 649:k 645:f 639:s 635:f 629:= 621:k 617:f 607:s 603:f 597:= 594:] 591:k 588:[ 585:N 569:k 559:k 557:f 539:. 531:k 527:f 517:k 513:f 507:= 504:Q 488:Q 484:. 481:k 469:T 465:T 461:s 458:f 441:. 436:N 432:/ 428:n 425:k 419:2 416:j 409:e 405:] 402:n 399:[ 396:x 393:] 390:m 384:n 381:[ 378:W 373:1 367:N 362:0 359:= 356:n 348:= 345:] 342:m 339:, 336:k 333:[ 330:X 317:m 313:x 293:n 286:f 282:k 277:k 256:, 247:f 235:k 230:) 225:n 221:/ 217:1 213:2 209:( 204:= 199:1 193:k 189:f 177:n 173:/ 169:1 165:2 161:= 156:k 152:f 134:k 123:k 118:k 114:f

Index

signal processing
frequency domain
Fourier transform
Morlet wavelet

waveform
C major
chord
frequency
musical pitches
fundamental frequencies
overtones

spectral width
octave
short-time Fourier transform
Hamming window

verification
improve this article
adding citations to reliable sources
"variable q transform"
news
newspapers
books
scholar
JSTOR
Learn how and when to remove this message
equivalent rectangular bandwidth
hyperbolic sine

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