Introduction to acoustics

Page 1: Introduction

• Title: The Science of Acoustics: Man, Space, and Sound

• Prepared by: Ar. Jay Jabonete, UAP

• Notes by: Ar. Danilo Ravina, UAP RMP

Page 2: Architectural Acoustics

• Definition: Architectural acoustics is the art and technique of designing spaces and structures to meet hearing needs.

• Importance: Knowledge of architectural acoustics allows designers to integrate sound control requirements with other building functions.

Page 3: Objective of Architectural Acoustics

• Designing considerations: Architectural acoustics ensures rooms or buildings provide comfort and facilitate communication, tailored to the building's specific purpose and use.

Page 4: Acoustical Objectives in Buildings

1. Control Echoes: Analyze room shape and sound absorbing materials for optimal sound distribution.

2. Reduce Sound Transmission: Implement proper insulation to minimize sound between rooms.

3. Isolate Noise: Prevent noise from machines and equipment from affecting the acoustic environment.

• Goal: Allow 'wanted' sound to be clearly heard while masking 'unwanted' sound to prevent annoyance.

• Design Stage: Acoustical objectives should be integrated early in the design process.

Page 5: What is Sound?

• Definition:

  1. The oscillation in atmospheric pressure detectable by the human ear.

  2. A form of energy that propagates in waves, converting into heat through material friction.

  3. The sensation from air pressure fluctuations perceived by the ear.

Page 6: Nature of Sound

• Essential Elements:

  1. Source of sound

  2. Medium or Transmission Path

  3. Receiver

Page 7: Source of Sound

• Definition: A vibrating body that converts energy into sound vibrations.

• Transducers: Devices converting energy into sound, e.g., loudspeakers, microphones.

Page 8: Transmission Path

• Definition: Any medium that allows sound vibrations to travel as waves.

  • Types:a. Airborne Sounds: transmitted through airb. Structure borne Sounds: transmitted through solid materials

Page 9: Receiver

• Definition: The human ear as the receiver of sound.

• Influences: External factors can affect how sound is received.

Page 10: Types of Sound

1. Music: Organized sounds with melody, rhythm, harmony.

2. Speech: Vocal expression to communicate.

3. Noise: Loud and harsh sounds classified as disorganized sound, e.g., street noise.

Page 11: Sound Waves

• Definition: Longitudinal waves through which sound energy travels, transporting energy away from the source without moving the material itself.

• Mechanical Requirement: Sound requires a medium for wave propagation; cannot travel through a vacuum.

Page 12: Components of Sound Waves

1. Cycle: Full particle circuit.

2. Frequency: Complete cycles per second, measured in Hertz (Hz).

3. Amplitude: Maximum particle displacement from equilibrium.

4. Period: Time for one complete vibration, measured in seconds.

Page 13: Properties of Sound

1. Speed or Velocity

2. Frequency (Pitch or Tone)

3. Power (Intensity or Loudness)

4. Sound Pressure

5. Threshold of Audibility

6. Threshold of Pain

7. Directionality of Sound Sources

Page 14: Speed or Velocity of Sound

• Sound travels at 330 meters/second at room temperature (20°C).

• Speed increases in denser media; faster in liquids and solids than in air.

• Temperature affects speed; sound travels faster at 30°C than at -17°C.

Page 15: Frequency and Pitch

• Definition: Frequency indicates pitch. Higher frequencies yield higher pitches.

• Measurement: Number of vibrations in cycles per second (Hertz).

• Hearing Range: Human hearing ranges approximately from 20 to 20,000 Hz, with sensitivity highest around 500 to 4,000 Hz.

Page 16: Power and Intensity

• Sound Intensity: Describes loudness/pressure against the eardrum, measured in decibels (dB).

• Decibel Scale: 0 dB signifies threshold hearing; 3 dB increase doubles sound intensity.

  • Examples:

    • Whisper: 15 dB

    • Normal Speech: 60 dB

    • Loud Talking: 75 dB

    • Shouting: 90 dB

Page 17: Conclusion

• End of Document