how to create perfect 10 dB sound using matlab?

Is this possible to measure sound level (db) of generated sound signal using matlab ? i have sent sound signal sound card .. but i dont know how to measure it or how to save that data for ploting nd convert it into dB? nd how to measure or create exact sound signal in dB?

[David Young]

I think it is probably the case that to give you a useful answer, it would be necessary to have detailed information about the sound card.

[Daniel Shub]

Can you explain a little more what you are doing? For example:

64-bit Linux with a M-Audio Delta 44 soundcard. The volume is set to the maximum. My sound card is connected to a 2W power amplifier which is connected to a Realistic Optimus Pro 7 speaker. My listening position is 1M away in an empty 10'x8'x10' room with 2'' Sonex foam covering all surfaces.

I have a vector in MATLAB with a maximum magnitude of 0.92, zero mean, and an RMS of 0.72. The stimulus is band limited between 250 and 4000 Hz. The spectrum of the stimulus is flat between 250 and 1000 Hz and sloping at 3 dB per octave between 1000 and 4000 Hz. I use soundsc with a sample rate of 8192 Hz.

I would like to create a sound with a level of 10 dB SPL A weighted.

With all of that information, there is a fighting chance that you can determine the sound level. You leave any of that out and it is hopeless. What information do you have.

[PRIYANK SHAH]

thank u daniel, I want to generate different types of tones using matlab, i m using dell inspiron14 laptop. i dont know about sound card.i m generating sound using function

>>soundsc(y,2000)

and y is a vector of 44100 raws and 1 column.

i have made this vector in xls file. elements are like 0, 0.1 ,.., 0.9, 1, 0.9, 0.8,....,0.2, 0.1, 0.0, -0.1, -0.2, ..., -0.9, -1 ,-0.9 ,-0.8 ,..., -0.1, 0.0 ,0.1, ..... so on..

and then i receive that sound using another lapy using matlab.

i got same sine wave but with increased amplitude. so how can i measure that sound in db ? or gime me formula to measure. and also give me trial and error method if available.

thank u very much . , David and Daniel..

[Walter Roberson]

*How* are you receiving the sound on the other laptop ?

At the moment, it does not look to me as you have anything close to the kind of setup that would be needed to prove that you had created a 10 dB sound.

[Daniel Shub]

Maybe he doesn't mean sound, maybe he wants something that is 10 dB re 1V or 10 dB re some MATLAB unit.

[Mustafa Samanci]

How can i calibrate my headphone with using Matlab? Is it possible?

Answer 1

[Walter Roberson]

You cannot do this without either (A) a lot of information about the amplifier circuit and the speaker, or else (B) a calibrated microphone whose signal you are reading in and using to adjust the values of your output.

The output to your sound card is just going to be a bunch of digital bits. The output of your sound card is just going to be an analog voltage signal with a fairly nominal power level such as 0.3V peak to peak.

Neither the bits nor the output voltage are going to be sound waves: you need at least a speaker for that, and fairly likely an amplifier to reach 10 dB.

Recall, though, that amplifiers and speakers almost never have "flat" response to all frequencies, so you are probably going to have to pick a frequency and work with it -- unless, that is, your 10 dB should refer to the total Sound Pressure Level, and even then there isn't much point emitting frequencies that are going to break the speaker or get cut off by the safeties built in to the speakers.

[PRIYANK SHAH]

thanks roberson and David,

but i hv to find the sound level of generaated signal. is it possible to measure db of signal for particular head phone or is it possible to save the signal which is going to sound card as output nd then measure it?

nd thanks again 4 replying.......