The constant-Q transform decomposes a signal into frequency bins whose bandwidth is proportional to center frequency, yielding a log-frequency time-frequency representation with constant quality factor Q. The analysis window length increases inversely with frequency: narrow bandwidth at low frequencies, wide at high. Parameters: number of octaves, bins per octave, reference frequency, quality factor Q. Persists as a spectrogram-like representation where frequency resolution follows a logarithmic scale, naturally suited to musical signal analysis where perceptual pitch resolution is logarithmic. [formal: constant-q-transform | substrate: mind | horizon: hours | explicit: yes | epoch: 0.01]
Accepted ontology entry
constant-q-transform
The constant-Q transform decomposes a signal into frequency bins whose bandwidth is proportional to center frequency, yielding a log-frequency time-frequency representation with constant quality factor Q. The analysis window length increas…
Definition
Why it is in scope
A human-made time-frequency signal representation that uses a frequency-scalable window (constant Q factor) to produce a log-frequency decomposition, built to persist through a filter bank whose bandwidth increases proportionally to center frequency, built to serve musical and spectral analysis where perceptual frequency resolution matters.
Names and aliases
- constant-q-transformen · CANONICAL
Relations from this entry
- cmspa8ycs04ocjlssyqljv74qDEPENDS_ON →
CQT decomposes a signal using a filter bank where each filter applies a window of increasing width (proportional to center frequency). Remove the window-function concept and CQT has no mechanism for its time-frequency decomposition. Constitutive: the algorithm IS windowed transforms stacked in scale.
- cmspdibrl04whjlssto99iiufDERIVED_FROM →
Constant-Q transform is a Fourier-like transform with logarithmically-spaced frequency bins where the ratio of center frequency to bandwidth (Q factor) is constant. It was derived from the Fourier transform framework by replacing the fixed sinusoidal basis with scaled window functions that maintain constant Q. The which-came-first test: Fourier transform (1807) predates CQT (1990s) and fed into its development.
- cmspdibrl04whjlssto99iiufDEPENDS_ON →
CQT is a Fourier transform variant using constant-Q windows. Remove the Fourier transform and the core spectral analysis computation vanishes — CQT cannot operate without it. Removal test passes. DEPENDS_ON holds.
- cmsplyfg905ubjlsscto9nfc0INSTANCE_OF →
CQT is a specific kind of time-frequency representation: it represents signals in joint time-frequency space with constant-Q (logarithmic) frequency resolution. A competent speaker calls CQT 'a time-frequency representation.' Per Law 9.
- cmspltmgd05tcjlsse8vqfce1DERIVED_FROM →
CQT builds on the time-frequency analysis paradigm pioneered by STFT. Which came first test: STFT (1940s) predates CQT (1970s); STFT's constant-resolution time-frequency representation concept fed into the variable-resolution CQT design.
- cmsqzfafz0068swynl7virfwrINSTANCE_OF →
Constant-q-transform IS a specific kind of time-frequency analysis — it provides a time-frequency representation with constant-Q resolution, complementing STFT's constant resolution and wavelet's constant percentage bandwidth. A competent speaker would call CQT 'a time-frequency analysis method.' Files against nearest kind.
Relations to this entry
No accepted relations in this direction.
Record identity
- Created
- Aug 13, 2026, 4:55 AM UTC
- Content hash
- fb9cc46d757fe682cf68aa5f46d1e7a51ae3533ea94aaf59694d176376eb2482