Amplitude

The Amplitude Is the Height of the crust in a sound wave and it affects the loudness of the sound, loudness of sound can be harmful if crossed the limits.

Db in SOUND

Amplitude or loudness of sound is measured in db (Decibels). Decibel is not an absolute scale, it is a relative scale, it is only used for measuring ratios, and that depends upon different situations. But there is no answer that what exactly is 1db as we know in kg or km.

Therefore these Assumptions come into play, which are different for real sound and audio.

When we talk about the Real sound, in order to measure loudness of sound, a level of the minimum sound (threshold) which is pure silence is set to be 0 db. And with that reference we can measure the loudness of the real sound in reality as we go up by 5db 10db 15db and so on. With these measurements it is assumed that loudness within 100db is safest sound that is audible. Maybe 115 db can be harmful.

Db in Audio

Now for Audio, It Is totally reversed, when we talk about decibels in audio 0db is the maximum value that any audio device can handle. And then all audio is based on negative values of decibels.  That is 0db, -5db, -10db, -15db.                                                                                                     

                             Max, loud, less loud, lesser loud and so on.

Frequency

Frequency is defined As the no. of cycles per second, its measured in Hz (hertz), and it effects The pitch of the sound, higher the pitch sharper will be the sound and lower the pitch the graver will be the sound. E.g. a female’s and a male’s voice in most cases (Deep or Bass).

Range of frequency a human ear can listen is known as the AUDIBLE range and the range is 20 Hz to 20000 Hz

Infrasonic (Below)   20 Hz - 20000 Hz   (Above) Ultrasonic

Frequency is harmless because we cannot listen to infra and ultrasonic frequencies.

Sound

Sound is Form of energy, which is in the form of waves.

Sound is created from a source of energy, and when sound is produced the constant air molecules (in Silence) are disturbed, and that disturbance is two way disturbance, and thus waves are created, which have peaks and troughs (oppressions and depressions). Humans have a little organ in our ears called the ear drum, the ear drum also vibrates in the exact same way the sound waves are vibrating.

The only difference between air and water is that we can see water waves but cannot see air.

Dynamic Range

The Difference between the highest and the lowest levels of loudness in audio is known as dynamic Range, i.e. –infinity to 0db.

In real sound the dynamic range is from 0db till the point our ears get damaged.

Phase

When two waves are totally identical, we say that the waves are in a phase.

Constructive Interference:

When we join the two identical waves then the resultant wave will be a wave having double the amplitude of each wave. This process is known as Constructive Interference.

Phase Cancellation:

But if two wave are totally identical (phase) but are inverse and they are added then the amplitude of the resultant wave will be cancelled out, then the there will be neither peak nor a trough and there will only be a straight line. This process is known as destructive Interference (Phase Cancellation).

 Good Examples: Karaoke Devices, Noise reduction Headphones etc.

Audio Sampling

When Sound is recorded in audio through any device it is known to be sampled, just like in images, pixels are the building blocks of the picture. When we talk about audio, samples are the building blocks of digital audio, The audio wave is sliced in tiny parts called samples, higher the sampling rate better is the quality of the sound (just like resolution).

Sample Rate: 
The sample rate is no. of samples per second. And the standard is 44100 Hz which Is good quality sound.

Difference Between Sound And Audio

Sound is the natural voice or sound that is produced from natural sources

But when our sound is recorded into digital energy it is converted into Audio

But what is the final destination of audio?

The Speakers! Where it is again converted into sound that reaches our ears

SOUND = Acoustic Energy             and               Audio = Electronic Energy