Measuring sound frequency.

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sana_akhtar

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Hey all

Can someone tell me that is there any instrument that can measure the frequency of noise? I have sound level meter but it measures sound pressure which I dont need. I actually want to know the frequency range of the noise being produced from a machine.
 

Hello,

I am trying to get a better picture of what you are looking for. So you have a sound signal with noise so you want to filter out your sound and find the noise frequency spectrum is my understanding. Can you explain the application a little bit more so I can get an idea of the end picture? There are a couple ways to accomplish this through DSP and filtering but we should know the parameters before we suggest anything.
 

There is an audio spectrum display included among the visualizations in Windows Media Player.

Look for 'Firestorm' (in the category 'Bars and Waves').

I don't know if there is any way to make WMP listen to a sound at the time it is made. If there were, then you could display its spectrum in real time.
Instead I believe you will need to record the sound into a computer, then open WMP, and play the audio file while watching the visualization.
 

Proper white noise has equal amplitude across ALL frequencies. Pink noise is white noise that has gone through a filter. Hum is at the local mains frequency. Oscillations/instability can result in a single or group of frequencies being produced. What you need is a spectrum analyser, you can see the spectral distribution and amplitudes of any peculiar spurious output. Failing that a wave analyser, like a calibrated radio receiver, only it receives audio frequencies.
Frank
 

We can help you better if you describe the noise.
Low frequency hum? Medium frequency roar? High frequency hiss? A low, medium or high frequency tone? Many people talking at the same time?
 

oh sorry.. I should have mentioned the detail.

Actually its a printing machine. While working, its sound/noise is above the save level near 95-98 dB. We want to work on this problem for the safety of operating staff. The instrument I have is sound level meter that actually gives intensity of sound/noise. I want to measure the frequency range of this noise. How can I without a meter?
 

A printer makes mechanical percussion sounds that have wideband frequencies. The peak sound level (that a sound level meter cannot measure) is probably much higher than the average level shown by the meter.
To prevent deafness the operating staff should use ear plugs certified to protect from loud sounds.

I don't think the frequencies make any difference. Too loud is simply too loud.

Minimum hearing protection results in everything sounding like a telephone: No high audio frequencies. What? Huh? Um? No I didn't hear that. What did you say?
 

In a noisy area, the problem is made worse by the sounds being reflected from hard surfaces. So look at the walls and ceilings of the room and consider hanging them with drapes (curtains). Industrial "silencers" are frames of metal, say 6 inches deep and 3 feet square, packed with glass fibre which is held in by a very open mesh grill (chicken wire). Trouble is they look awful! "Quiet rooms" , have pyramids of glass fibre stuffed materials fixed to all surfaces. See :- https://en.wikipedia.org/wiki/Sound_dampening
Frank
 
Is there any frequency measuring meter?
I want to check the frequency range of a noise being produced from a printing machine (industrial level).
 

Recent digital sound level meters are equipped with a spectral display which would be sufficient to get an idea about the dominant frequency components of the said machine noise. Most acoustic experts will probably know when hearing the noise.

Frequency spectrum matters when chosing appropriate noise absorption solutions. 95 - 98 dB (dB A or dB C, which distance) is quite a lot and can't be easily reduced to a level where attendance of people without hearing protection would be tolerated by safety standards.
 

There are graphic equalizers which have a grid of leds, showing amplitude of each frequency band.

I purchased one cheap on Ebay. It is stereo, 10 bands per channel, 10 led's per band.

The input needs to be line level. A mic signal would need a pre-amp.
 

NTi has many features and high resolution spectrum analysis. But I'm not sure if you actually need any of it's features.
 

Noise is many frequencies. You do not need to measure the frequencies because you cannot reduce their loudness.

Instead buy noise-cancelling headphones that work well because they have microphones inside and outside the earcups that pick up the noise and subtract it from your hearing. I do not know if there is a certification for noise-cancelling headphones that show how much noise loudness they cancel like there is for ear plugs.
 

Thanks all

Can you please tell me a sound spectrum analyzer with reasonable price and good results? Any one that is made in china
 

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