HardNLPnlp-193

MFCC Coefficient Value

Problem

Return one MFCC coefficient from mel energies using the DCT-II: sum over k of log(max(E_k, 1e-10)) * cos(pi * n * (k + 0.5) / K), where K is the number of mel bands and n is the coefficient index.

Energies below 1e-10 are clamped before taking the log.

Hint

Coefficient 0 is the sum of log energies; higher coefficients oscillate with cos.

Test cases

case 1

in: [[1,1,1,1],0]

expected: 0

case 2

in: [[1,2,4,8],1]

expected: -2.1864094216025802

case 3

in: [[1,2,4,8],0]

expected: 4.1588830833596715

case 4

in: [[1],0]

expected: 0

case 5

in: [[1,2],0]

expected: 0.6931471805599453

Starter codePython

import math
def mfcc_coefficient_value(energies, n):
    # Your code here
    pass

5 test cases · run your code against them in the editor