Signal Processing Stack Exchange
Signal Processing Stack Exchange

Questions tagged [spectrogram]

A spectrogram is a time-varying spectral representation (forming an image) that shows how the spectral density of a signal varies with time.

Also known as spectral waterfalls, sonograms, voiceprints, or voicegrams, spectrograms are used to identify phonetic sounds, to analyse the cries of animals; they were also used in many other fields including music, sonar/radar, speech processing, seismology, etc. The instrument that generates a spectrogram is called a spectrograph and is equivalent to a sonograph.

Source: Wikipedia – Spectrogram

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Reconstruction of audio signal from Spectrogram

I have a set of songs for which I extracted the magnitude spectrogram using a Hamming Window with 50% overlap. After extracting the spectrogram, I did some dimensionality reduction using Principal Components Analysis (PCA). After reducing it to…
user76170
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Improving spectrogram resolution in Python?

I'm using the specgram() function in matplotlib to generate spectrograms of speech wave files in Python, but the output is always of vastly inferior quality to what my normal transcription software, Praat, can generate. For example, the following…
Alek Storm
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What is the maximal frequency resolution for Matlab's STFT implementation spectrogram()?

Matlab's spectrogram() function calculates the STFT of a signal. It describes its NFFT argument as follows: S = SPECTROGRAM(X,WINDOW,NOVERLAP,NFFT) specifies the number of frequency points used to calculate the discrete Fourier transforms. …
Andreas
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Creating a spectrogram

I've been trying to work out the logic for this task, and plan to use the KissFFT source package to perform the fast fourier transform. Please let me know if this looks about right: Allocate an FFT structure, ie.…
raynebc
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Reconstruction of Audio Signal from its Absolute Spectrogram

I have the absolute Spectrogram of an audio signals. I lost the phase data of the Spectogram because of various processing applied on the original spectrogram of the signal. I'm trying to reconstruct the audio signal in a meaningful (Audibly) manner…
Royi
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interpret wavelet scalogram

My knowledge of wavelets is less than epsilon. Bear with me. If I have a signal of two well separated sinusoids (15 and 48 Hz) plus some random noise, I can clearly make out the two in a spectrogram (the two stripes in my picture); t=0:0.002:1; %…
user1641496
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Converting mel spectrogram to spectrogram

I have a set of songs for which I extracted the STFT (Short-Time Fourier Transform) and used the magnitude spectrum $|S|$ to calculate the mel spectrogram by using a mel filterbank matrix $M$, so $X=\log(M\times |S|)$. I want to know is there any…
user76170
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Vertical lines noise in spectrogram

I have started looking into DSP and made an implementation of short-time fourier transform, using kissFFT to perform the FFT. I then render a spectrogram. An example image that I have generated can be seen below. On top is the spectrogram of a music…
Advecticity
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Spectrogram Analysis

I have four .wav files and each contain bird chirps. Given an input .wav file, I need to find out which bird it is. I have some basic understanding of signal processing. I have used spectrogram to analyze my audio files and now I don't know how to…
Prashant
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FFT to spectrum in decibel

Here is a 10 seconds-long 440hz sine wave normalized at $0\textrm{ dBFS}$. When computing the STFT (with the code below) of this audio file, I noticed that max(abs(STFT)) is around 248.33. (more generally, it seems to be approximately fftsize/4…
Basj
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How do I plot the spectrogram of a wav file?

I am dabbing a little bit into signal processing on MATLAB. And I have the following question that I would like to know the answer to. What has to be done : Plot the Spectrogram of an audio file. What I know : Since its an audio file, I use wavread…
hRob
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Convolving With half-Hanning

The goal is to get a 200ms decaying delay of an audio signal while preserving the sharpness of attacks to mimick human perception of sound. The paper I'm following convolves a 200ms half-Hanning window with each frequency band to simulate it. I'm…
Newmu
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Audio Processing - How to create a spectral pitch display?

I want to create an application that analyzes human voice pitch, but spectrograms are very noisy. However, in Adobe Audition, there is a feature called the spectral pitch display, and it successfully filtered the spectrogram so that only relevant…
Hykilpikonna
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log(conv) vs conv(log)

Suppose an arbitrary, strictly positive $x[n]$, transformed as $$ x_l[n] = \log(1 + C x[n]) \tag{0} $$ where $C$ is freely chosen. Given the following, where $h[n]$ is a Gaussian lowpass filter (or any other strictly positive…
OverLordGoldDragon
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Using MATLAB's Spectrogram Function for Analysis

In the documentation - sepctrogram(). Question 1)s = spectrogram(signal) and spectrogram(signal) are two commands to plot the spectrogram. However, the variable s is complex valued. I am unable to understand which output of the spectrogram is used…
Sm1
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