How is the audio quality of a phone measured?
In: Technology
Firstly by the taste in music of the owner.
Then by its ability to reproduce a range of frequencies.
You play a set of tones, the record those with a microphone or through a jack depending on what you want to measure, the replication or the speaker.
When you tell the driver (speaker) to play set tone at set volume, you can measure that from the signal or with a microphone. You then compare that to a reference chart of desired results.
You want different kinds of sound profiles for different uses, for media you want as accurate and broad as you can. For speech you want to limit the range to only speaking frequencies to make sure it can be heard as clearly as possible.
They can measure how it responds to different frequencies, you make it produce a specific pitch and measure with an instrument how loud each frequent comes through, usually you want every frequency to be as close in volume to the others as possible
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Frequency response.
Basically, all that reproducing sound is, is playing different frequencies of sine waves (the ones that sound like this: https://www.youtube.com/watch?v=3FBijeNg_Gs ) over top of each other to represent more complex waveforms that then can resemble music or speech (if you want to learn more about it – a bit out of ELI5 territory, more like ELIACollegeStudent, look up fourier transforms and how they relate to the MP3 audio codec).
The speaker is basically just a piece of material that gets pushed back and forth to transform those waves from an electrical signal to a physical signal, pushing the air, like a fan. That then is the sound we hear.
But, the efficiency of doing that isn’t always the same for every frequency. It might be lower for a high frequency, higher for a middle frequency and so on. In the end, what you want to have for good audio quality is 2 things:
– A good frequency response curve – either flat – mostly used for studio monitors, or a slight v-shape – mostly used by consumers, because it makes music ‘sound better’, since most people like to hear more bass and treble
– Distortion free sound reproduction. Basically, that the speaker does what “it is told”, and not something different. You know that iconic distorted electric guitar sound? That’s distortion. In electric guitars, it can sound pretty cool, but compare what a clean, undistorted electric guitar sounds like compared to say, what you might find on master of puppets by metallica. You don’t want your entire song to sound like that guitar instead of what it should sound like.
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