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.

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312 views

What is the autocorrelation equivalent of the spectrogram called?

I'm very knowledgeable about the differences between the Fourier transform, and the autocorrelation; mainly that one converts the time domain to the frequency domain, and the other finds periodicities ...
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257 views

Points of interest in a spectrogram

We have several audio tracks, all of which are different versions of the same track under one type of distortion: the speed of the track is increased by a constant factor K (hence frequences are ...
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1answer
52 views

How to interpret these MP3 spectrums?

Recently, I found I had this song duplicated in my music library, but when listening to them I noticed one version was of noticeably higher quality than the other despite both claiming to have a ...
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167 views

Reconstruct signal from its Spectrogram only

The spectrogram of a signal throws away the phase information, but it is said to be possible to reconstruct the signal only from the spectrogram [1] via $$s(t) = \frac{1}{2\pi s^*(0)}\int_{-\infty}^{\...
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194 views

Help detecting target in pulsed radar signal

This signal is from the Pasternack $2.4\textrm{ GHz}$ development kit. The saved signal appears to be the pulsed waveform. It is sampled at $20\textrm{ kHz}$ for $4130$ points. I recorded a ...
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189 views

Normalize harmonics to the same fundamental frequency in a time series using MATLAB

I'm a bit new to DSP (so apologies if I get the terminology incorrect) and was wondering if the problem I have is standard. I have measured a time series of a fan and noticed that the my spectrogram ...
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1answer
228 views

Unexpected peaks in spectral analysis

I am doing the spectral analysis of some antenna recorded signals by computing PSD (logarithmic absolute value of the FFT) and the spectrogram of the signal. The problem is that I get some unexpected ...
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26 views

When do phases not exist for spectrograms?

I have been reading a paper on the "Single pass spectrogram inversion" and I came across this in the Introduction part. In many applications, the analysis and modification of the Short-Time ...
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1answer
37 views

Normalizing vectors to be the same size to retain PSD data

Context: PSD=periodogram(y) in MATLAB gives the PSD (power spectral density) estimate of a sound-source signal. I want to find the local maximum within 3 different ...
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2answers
470 views

Quantify the difference between two audio spectrograms

I have two speech signals of the same length. They contain the exact same speech content but are recorded from two different microphones. I want to compare the differences between them. 1) Assuming ...
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1answer
102 views

How can you 'perfectly' reconstruct phase for transients in a modified audio absolute spectrogram?

I am currently working on the absolute spectrogram of an input audio signal. I am using non-negative matrix factorization to separate out the rhythmic components (bass drum, snare drum and hi-hat) of ...
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1answer
417 views

Is the Auditory Spectrogram the same as the Magnitude Spectrogram?

This is in the context of speech signals. The magnitude spectrogram is computed by framing the signal into short time windows, applying a hamming (or similar) window, computing the fft over each ...
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155 views

How to calculate spectrogram from nonstationary, nonuniformly sampled signal

I have a high resolution 3D spatial signal (xy-elevation data collected via Terrestrial Laser Scan) with very nonuniform sampling (holes/shadows due to vegetation; point spread varies as a function of ...
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1answer
111 views

Continuous wavelet transform subsampling at lower frequencies?

I am not completely confident in my understanding of wavelet theory, but since I am currently in the process of creating a CWT scalogram tool, I have to ask: Is there a theorem allowing us to ...
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441 views

calculating SNR from dbfs (using spectrograms)

I've the spectrogram of both noise and signal (both 5 seconds). Below image shows an example of the signal spectrogram: The colour of the spectrogram shows the intensity in dbfs (from 0 dbfs to -120 ...
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78 views

Values (amplitudes) of the CWT and their relationship to waveform amplitudes?

I'm coding up a scalogram in C++. Right now it calculates a single row of the CWT matrix and immediately maps it to a line of pixels. Trouble is my colouring scales with the values of the transform ...
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566 views

How does the size of a spectrogram relate to window length and frame rate?

I'm trying to understand the methodology from section 4 in this report about audio classification but I have some trouble understanding how they pre-process the data (dsp is not my area). $30$ ...
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387 views

removing noise from audio

I have an audio file, in the range of 4 kHz to 120 kHz. I want to remove the lines that are not harmonic and are recognized as environment noise. the energy of the signal in this interval for each ...
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66 views

Epoching Data with no Events in mne?

I am new to Python and signal processsing, and I'm trying to create a spectrogram of EEG data taken during a course of general anesthesia. I would like to use MNE's ...
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104 views

difference between logged power spectrum and power spectrum?

What is the difference between a logged power spectrum and power spectrum... Well the log part. So can a normal power spectrum be converted to a logged power spectrum just by taking the log of the ...
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292 views

4 Hertz Modulation Energy

I am trying to distinguish between speech signals and music signals using feature extraction and SVM. I am looking for features to include for this purpose. While going through literature, I came ...
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1answer
631 views

How can create a .wav bar based spectrogram on matlab?

How can I create a bar based spectrogram that updates as a .wav file is playing. This is commonly found in music players. Here is an example below: I am able to display a amplitude/frequency graph ...
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1answer
4k views

Spectrogram, time vs frequency localization, and length of signal

So I'm having some trouble conceptually and am hoping somebody can clear something up for me. This is long and I apologize for that but I want to provide as much information as possible so that the ...
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490 views

Converting musicg spectrogram output to dBFS

I'm trying to convert musicg Spectrogram output to dBFS. With 16-bit signed integer PCM audio, and an FFT length of 2048, I'm trying to analyze the spectrogram for an audio file to determine things ...
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353 views

Understanding PCA

OK, I have tried to ask the same question in the math site on stack exchange but no real joy. Apologises I'd this is the wrong forum. I am trying to compute the PCA of a spectrogram.. It is 486x128 ...
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1answer
27 views

High resolution spectrograms

I have a recorded audio signal that I would like to convert into spectrogram with the highest possible yield of information. The audio clips I am working with is about 30 ms long and contains ...
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2answers
30 views

Augmentation for EEG signal classification using Deep Learning

Augmentation is a technique that we use in deep learning for expanding the training dataset. It includes different ways of modifying an image and adding it to the training dataset. My question is if ...
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5 views

Why can ARSS not recreate audio from a spectrogram without sounding muffled?

Why do ARSS and all audio to spectrogram then back to audio program's create audio files that sound muffled? I know their is some physics and math with the short-time Fourier transform and etc. I ...
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1answer
31 views

Spectrogram Time Resolution with Overlap

I understand that the time resolution of a spectrogram with no overlap is the sampling frequency divided by the window length. How does this change with, say, 50% overlap? Does this double the time ...
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26 views

Optimizing Spectrogram Parameters

I'm looking for references that explain the trade-offs between more averages with shorter fft sizes or longer fft sizes with fewer averages when generating a spectrogram to perform energy detection of ...
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15 views

Spectrogram of chirp sequence radar signals

I am confused as to whether SFFT makes sense to process chirp sequence signals. The radar fires up a sequence of 100 linear ramps with that are only interrupted by the very short period in which the ...
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18 views

finding harmonics from fundamental

https://s3.amazonaws.com/izotopedownloads/docs/rx700/en/interactive-tools/index.html#selection-tools From the above link, under the "Magic Wand" tool description, how does that algorithm work? In RX,...
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171 views

How to Extract frequency bands from Short-time Fourier Transform?

I am reproducing the results reported by the author in a research paper. In which he takes the STFT of EEG signals. The input data has a shape of (1 X500) and I used Scipy library built-in function to ...
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221 views

Recover Audio from Spectrogram Image

I have applied transformation(Constant Q Transformation) to my audio time domain signal, this gives me Frequency vs Time representation. Now, the CQT values consists of complex values(84*260), but ...
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33 views

Scipy Welch's gives different first element

I've re-implemented Welch's method and want to compare it to scipy.signal.welch. However, the first two and last elements of the resulting array are different. My ...
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89 views

How to use a context window to segment a whole log Mel-spectrogram (ensuring the same number of segments for all the audios)?

I have several audios with different duration. So I don't know how to ensure the same number N of segments of the audio. I'm trying to implement an existing paper, so it's said that first a Log Mel-...
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86 views

How can I calculate the Number of bins per octave?

I am trying to calculate the Constant Q Transform for Monophonic audio using Python. The Python has the library to calculate the CQT , the default value of num_bins_per_octave is 12. How would one ...
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63 views

How to know the time of my window to calculate the STFT with python knowing only the length?

I am trying to implement a work presented in an IEEE paper where they have mentioned that the STFT was performed on the signal measurements to obtain a spectrogram with no overlap window of 3 min : I ...
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1answer
58 views

Fourier like spectral analysis with uneven intervals and redesigned DFT matrix

I intended to use a discrete Fourier transform (DFT) on a time series sampled at uneven intervals. What I did was to calculate a DFT matrix where the elements are the values at the uneven locations ...
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131 views

Mirrored Spectrogram Mp3

First of all sorry if this is a stupid question, but I am an absolute beginner in this field and have been trying for days now. I'm working on a java program that uses fft to analyze audio files. To ...
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16 views

time-frequency masking with shared properties between vector masks

I am working on a source separation problem and I have a logical mask that when applied to the STFT matrix, gives me expected results. The problem here, is that the mask is based on a spectral feature,...
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1answer
202 views

how to create a harmonic mask from fundamental frequency?

Using an algorithm that gives the fundamental frequency across time, example https://www.mathworks.com/help/audio/ref/pitch.html (or some other one?) how would I then use that, to create a harmonic ...
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113 views

Spectrum of received signal from radar fm-cw

I obtained actual data from a researcher, consisting of a matrix composed of several received signals from an up-ramp fm-cw radar. Wouldn't be reasonable to plot the spectrogram of a ramp up and ...
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217 views

How to manipulate output of Matlab's 'spectrogram' function for additional spectral analyses

all, I have an audio recording that contains several frequency-modulated elements (think animal calls like birds/bats). I have read this file into Matlab using 'audioread' and plotted the oscillogram ...
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248 views

Hilbert Spectrum vs. STFT

If I wanted to plot a spectrogram of a signal, I would by default use the Short Time Fourier Transform. However, the Hilbert transform does something similar: it lets us calculate instantaneous ...
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319 views

Smooth looking spectrogram display

I'm working on a simple sound analyzer application and a main feature of this program is the spectrogram display. I want this spectrogram to render fast and to be good looking while preserving all the ...
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1answer
544 views

Comparing band-pass filters and convolutional kernels?

I am currently working on extracting features for speech recognition purposes. I wanted to try an approach similar to MFCC features in which the center frequency of each band pass filters are placed ...
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268 views

Proper way of representing Static, delta, delta delta in a plot

I am currently working on recreating the result of this paper. The paper is about applying cnn in speech recognition, in which cnn is used to for feature extraction, for which a proper way of ...
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142 views

Frequency range of acoustic feedback

What is the frequency range in which acoustic feedback can be found? Most importantly, is there some lowest frequency below which one can expect not to find any feedback? My conclusion from the ...
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350 views

Looking for an algorithm that computes weighted average of frequencies intensity from narrow band in spectrograph

I am searching for the algorithm that takes (audio) signal as an input and outputs weighted intensity of the frequencies of some narrow band (axis X) in time (axis Y). Frequency in the middle of that ...