Acoustics

Acoustics is defined as the science that deals with the production, control, transmission, reception, and effects of sound (as defined by Merriam-Webster). Many people mistakenly think that acoustics is strictly musical or architectural in nature. While acoustics does include the study of musical instruments and architectural spaces, it also covers a vast range of topics, including: noise control, SONAR for submarine navigation, ultrasounds for medical imaging, thermoacoustic refrigeration, seismology, bioacoustics, and electroacoustic communication.

(Ref: BYU Acoustics Research Group)

The perceptional capabilities of the human ear, three different frequency ranges are distinguished. The range of hearing stretches from about 16 Hz to 16 kHz. Lower frequencies are called infra-sound, higher frequencies are called ultra-sound.

The field of acoustics can be subdivided into several special topics such as:

Theoretical acoustics, Nonlinear acoustics, Underwater acoustics, Ultrasound, Vibrations, Noise control, Room acoustics, Building acoustics, Electroacoustics, Acoustics of the ear.

Speed of sound in air:

temperature [◦C]   | speed of sound c [m/s]

   0                                                                 331.3

                        10                                      337.3

                        20                                      343.2

Density of air at sea level:

temperature [◦C]   |  density of air ρ [kg/m3 ]

        0                                              1.292

     10                                               1.247

     20                                               1.204

Acoustic impedance:

temperature [◦C]   |   ρc [Ns/m3 ]

       0                                       428.0

    10                                       420.5

    20                                       413.3

(Ref: Kurt Heutschi)