Architectural acoustics

Sound

Sound is a vibration in an elastic medium  such as air, water, most building material and earth 

Hearing

Hearing, or auditory perception, is the ability to perceive sound by detecting vibrations changes in the pressure of the surrounding medium through time

logarithmic dependence of hearing on stimulus

Amplitude

Amplitude is the size of the vibration, and this determines how loud the sound is. larger vibrations make a louder sound.

Amplitude is important when balancing and controlling the loudness of sounds, such as with the volume control on your music player.

Frequency

Frequency is the speed of the vibration, and this determines the pitch of the sound. 

Frequency is measured as the number of wave cycles that occur in one second.  The unit of frequency measurement is Hertz (Hz for short).

Particle Velocity

Velocity of a particle in a medium as it transmits a wave, in sound it is longitudinal wave of pressure disturbance that travels through a medium

Sound Power

Sound power is the energy rate – the energy of sound per unit of time measured in Watts (W )

I = p \ v

Intensity (I) in  W/m2

Pressure (p) in Pascal Pa

Particle Velocity (v) in m/s

Sound Pressure

Sound pressure or acoustic pressure is the local pressure deviation from the ambient (average, or equilibrium) atmospheric pressure, caused by a sound wave.

Sound Intensity

Sound intensity also known as acoustic intensity is defined as the power carried by sound waves per unit area

P = AI

Power (P) in  W

Area (A) in m2

Intensity (I) in  W/m2

Loundness

Loudness is the way in which we perceive amplitude. A particular change in amplitude is not necessarily perceived as being a proportionate change in loudness. That is because our perception of loudness is influenced by both the frequency and quality of a sound(timbre,लय) .

loundness is measured in unit of Phon

Phon is loundness experienced by listener

Note (from “notation”)

स्वर Note is a certain frequency that you write or read.

Tone

सुर  Tone is a certain frequency that you hear

Pitch

स्वरमान Pitch is a certain frequency that you sing or play , The sensation of a frequency is commonly referred to as the pitch of a sound. A high pitch sound corresponds to a high frequency sound wave and a low pitch sound corresponds to a low frequency sound wave

Timbre

लय Timbre is a certain quality (or color) of the tone, depending on the instrument and how you play/sing the tone.

1.Sound absorbed in the air, also applicable to reflected sound.

2.Sound reflected from the wall surface.

3.Sound absorbed at the wall surface or its surface finish.

4.Sound conducted by the wall to other parts of the structure.

5.Sound emitted by resonance of the wall in both directions.

6.Sound inter-reflected between bounding surfaces, setting up reverberation.

7.Resonance of the enclosed volume of air by direct cross reflection

• Reflection
• Absorption
• Refraction
• Diffusion
• Diffraction
• Transmission
• Reverberation and Echo