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.

Filter by
Sorted by
Tagged with
0
votes
1answer
65 views

Extracting audio from picture of time-domain signal

I saw this nifty art thing where they dress up the time-domain audio signal in some pretty way. https://www.etsy.com/ArtbloxShop/listing/621561709/sound-wave-art-custom-soundwave-print My question is ...
0
votes
1answer
61 views

How to classify the movement type of a target into two categories(direct motion or else) by using a doppler radar?

How to classify the movement type of a target just into two categories(one is direct motion which is almost straight line movement and the other is anything else) by using a doppler radar with a ...
0
votes
1answer
2k views

How to go from wav file to spectrogram back to wav file in python?

Close to this question but different : Wav To Spectrogram, Back To Wav I already posted this on StackOverflow(https://stackoverflow.com/questions/54743968/how-to-go-from-wav-file-to-spectrogram-back-...
0
votes
0answers
421 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 ...
0
votes
0answers
49 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 ...
0
votes
2answers
48 views

What is Causing a Noise Signal in USB Audio Recording?

I am experiencing the following peculiar noise signal when recording from my Behringer Xenyx Control 2 over USB. There is frequency at around 2293 hz as show: And over time, it produces the ...
2
votes
0answers
203 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 ...
0
votes
0answers
169 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 ...
0
votes
2answers
609 views
0
votes
0answers
82 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 ...
0
votes
1answer
565 views

Audacity Spectogram view: how to see exact frequency and intensity under the cursor?

In the Spectogram view, simply clicking anywhere with the selection tool gives a vertical line to the top ruler, and shows at the bottom the exact sample, H:MM:SS, or other time coordinate you'd want. ...
0
votes
2answers
254 views

Different ways of decomposing signals into sinusoids

For purposes of generating a spectrogram, the signal can be divided into overlapping chunks, each chunk multiplied by a window function and transformed to frequency domain using Discrete Fourier ...
0
votes
1answer
45 views

What's the right scale to represent a frequency spectrum?

To represent a 16 bits temporal spectrum, it's "easy" : my scale is going from -32000 to +32000. But What's the scale for a frequency spectrum ? I made that try : I calculated a pure single frequency ...
0
votes
0answers
193 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 ...
-1
votes
1answer
42 views

When does a color channel such as RGB carry more info than a grayscale channel or image?

Typically a gray-scale image gives us more information about an image in terms of a signal processing problem. But when does a color channel carry more info than a gray-scale channel? I understand ...
0
votes
2answers
3k views

Wav To Spectrogram, Back To Wav

Currently, I'm writing a Python script, which should do the following: read an audio file respectively a wav file via scipy.io.wavfile.read(). calculate the spectrogram of given wav file. write the ...
19
votes
4answers
22k views

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 ...
1
vote
2answers
94 views

Is there such thing as harmony independent timbre characteristic of a sound?

I was wondering if any of you know about any technique to extract a harmony (e.g. harmony in a shape of a chromagram) independent timbre characteristic of a sound frame. What I'm after is a version ...
1
vote
1answer
101 views

Spectrogram of 493 signals at a time [closed]

I have been working with some seismic data and recently submitted a paper to a journal. My seismic data has 493 traces: each trace are 8300 seconds long with sampling frequency of 2000 Hz. One of ...
0
votes
1answer
302 views

Spectrogram Interpretation

I collected vibration data (amplitude and time) on a component that was attached to an engine. Using MATLAB I plotted a spectrogram to see what frequencies it vibrated at. The code: ...
5
votes
3answers
25k views

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 ...
1
vote
0answers
312 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 ...
2
votes
2answers
170 views

Recommended resources for noise reduction

I know the question What Resources Are Recommended for an Introduction to Signal Processing (DSP)? and I have already read some general DSP books, such as Rick Lyons's "Understanding DSP," and also ...
1
vote
1answer
604 views

Spectrogram with square or non-square magnitude of STFT: power vs. magnitude

As seen in this question and answer, to do a spectrogram, it's common to plot either: the square magnitude $|\text{STFT}(\text{frame}, \text{bin})|^2$ ("power spectrum") the magnitude $|\text{STFT}(\...
1
vote
1answer
595 views

Calculating SNR from Frequency-time domain

I tried to analyse the time-frequency of specific appliances. As it shows in the following frequency-time graph I have High frequency noise from different appliances here. 4096 is the number of ...
0
votes
2answers
285 views

Window length in matplotlib's specgram

In the paper about speaker verification I can read that Two quantities have to be set: the length of the window and the shift between two consecutive windows. For the length of the window, two ...
0
votes
1answer
53 views

Phase of a signal with multi delayed windowed (rectangular window) signal with different amplitudes

I have a signal $x(t)$ which is composed of multi delayed linear chirps with different amplitudes and phases but they share the same $w$ and $\alpha$, the signal can be expressed as follows: $$\...
0
votes
2answers
3k views

Spectrogram from scipy.signal with Python

To test the python spectrogram (from scipy.signal) , I've created a signal with 2 harmonics: 2 Hz and 8 Hz. Then I've added 50Hz noise and a trend (https://i.imgur.com/t1SnQck.png). I wanted to ...
0
votes
1answer
795 views

How do I apply a binary mask and STFT to produce an audio file?

So here's the idea: you can generate a spectrogram from an audio file using shorttime Fourier transform (stft). Then some people have generated something called a "binary mask" to generate different ...
0
votes
0answers
149 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 ...
0
votes
1answer
208 views

What unit is the z axis of a power spectrogram of audio?

the question might seem dumb but since I tried it out and got values well above 2000 (watts?) it got me thinking... Check this out: ...
0
votes
1answer
243 views

1D signal to 2D spectrogram

I struggling at transforming a 1D breathing signal into 2D spectrograms, power spectral density as a function of time and frequency. Does anyone have an idea about that?
0
votes
1answer
108 views

nearest neighbor implementation matlab

I am trying to implement this research paper: I understand everything in the paper except the part about the nearest neighbors calculation (section 3). The only MATLAB function I can think of that ...
2
votes
1answer
5k views

scipy.signal.spectrogram

I want to do time-frequency analysis of a signal. So i decided to use spectrogram function from scipy. This function returns, three parameters f,t,Sxx. I am using below arguements: x : my signal fs : ...
0
votes
0answers
290 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 ...
1
vote
1answer
157 views

CMV: COLA constraint is not necessary

In the literature on the short-time Fourier transform (STFT) it is often stated or implied that the constant overlap-add (COLA) constraint must be satisfied in order for the STFT to be invertible. ...
0
votes
2answers
373 views

How to determine the frequency of each row in a MATLAB spectrogram

I recently learned how to manually compute a spectrogram of an audio signal, which is essentially a matrix. Each column corresponds to a time frame (e.g. 10 ms or something) but I'm asking which row ...
0
votes
1answer
455 views

chirp signal - Frequency spectrum characteristics

I am confused with my own intuition of the frequency response of a chirp signal. In this case, the chirp signal is a frequency modulated signal with initial frequency starting at 100 Hz and ending at ...
1
vote
1answer
288 views

Apply windowing before FFT or after?

I am computing a spectrogram and I've found a code example online which goes like this: ...
0
votes
1answer
226 views

Add noise/signal to mel log spectrogram

I have a predicted mel log spectrogram $S$ and I want to add a noise signal $\eta$ to it. S = log(mel-filterbank(abs/real part of(stft(signal))) The naive way ...
0
votes
2answers
177 views

Matlab: is a highpass filter what I want, to obtain my required spectrogram? How do I design/apply this? (pic included)

The axes are wrong in the spectrogram. I have an audio wav file, and I know the sampling rate. this is read into the audioData variable. The audio is 1 channel. selected window length I believe (can't ...
3
votes
0answers
177 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}^{\...
0
votes
1answer
74 views

is there a way to apply a median filter diagonally?

For example, some studies show how to smooth a spectrogram with a 2D median filter vertically and horizontally (along time or frequency). My question is how would I apply 2D median filter along the ...
2
votes
1answer
261 views

Distinguish harmonic sounds from non-harmonic

I am trying to distinguish harmonic sounds in the range from $100\rm \ Hz$ to $1000\rm \ Hz$ in my audio recording. I attach the spectrogram ($y$-axis is freqeuncy and $x$-axis is time) of a typical ...
-1
votes
2answers
2k views

STFT computation

I'm trying to compute the STFT by my self. Thus, I wrote the following code: ...
4
votes
1answer
1k views

Is it possible to recover a waveform from spectrograms of magnitude *and* phase?

It is my rough understanding that a typical spectrogram discards phase information by squaring only the real-valued part (magnitude) of the STFT (I know it's not quite this simple, but feel free to ...
0
votes
2answers
128 views

What's a good physical description of the following matlab code?

I've inherited some matlab code and I can't really understand what the resultant signal really means. The input is audio and the code first performs an STFT/spectrogram (sliding window FFT of size ...
0
votes
3answers
609 views

Guitar fundamental frequency vs pitch

When a note is played on the guitar, is the fundamental frequency always the strongest one or could a harmonic be the strongest one (in terms of amplitude). When could that happen? Also, when playing ...
-4
votes
2answers
65 views

What can i find in a spectrogram?

What information can i read from this spectrogram? I have 2 signals, the first one a sine and the second one a sine with noise
0
votes
0answers
293 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 ...