Sounds Good 💥 | Weird But True Full Episode | @natgeokids

Key Concepts

• Sound as vibrations and soundwaves
• Sound transmission through different mediums (gas, liquid, solid)
• Human ear anatomy and sound perception
• Noise cancellation (passive and active)
• Reverberation chamber vs. anechoic chamber
• Frequency (Hertz) and Intensity (Decibels) of sound
• Subjectivity of sound perception (good vs. bad sounds)
• Soundproofing techniques

What is Sound?

Sound is defined as vibrations that cause particles to wiggle, creating a domino effect known as a soundwave. Sound is not a physical thing but a wave of vibrations that can travel through gases (like air), liquids, and solids. Sound travels four times faster in water and 15 times faster in steel than in air.

How Ears Work

Sound waves enter the outer ear, travel through the ear canal to the middle ear, vibrating the eardrum. These vibrations are transferred to the inner ear, where they move fluid that stimulates tiny hairs on the cochlea. These hairs create nerve signals that the brain interprets as sound.

Noise Cancellation

Noise-canceling headphones use two techniques:

• Passive Noise Control: Physically covering the ears to block sound. This can be achieved by creating a seal around the ears or inserting something into the ear canal.
• Active Noise Control: Using a microphone to register incoming noise and playing a sound with a waveform exactly 180° opposite to cancel out the noise.

Orfield Laboratories Visit

The Crafteroons team visits Orfield Laboratories in Minneapolis, Minnesota, to learn about soundproofing. Steve Orfield, a sound expert, explains that the lab focuses on research, testing, and design related to how products sound to users. He emphasizes that sound is a full-body experience, and senses work in combination.

Equipment at Orfield Laboratories

• Sound Level Meters: Used to measure sound levels.
• Head and Torso Simulator (HATS): Records sound using artificial ears with microphones to mimic human hearing, providing a three-dimensional sense of sound.
• Acoustic Camera: A disc with 128 microphones that visualizes sound by showing where it originates from a device.

Reverberation Chamber

A room that is 99.9% reflective, meaning sound bounces around without being absorbed. The walls and ceilings are made of solid concrete block.

Anechoic Chamber

A room that is 99.9% absorbent, the opposite of a reverberation chamber. It has padding on all surfaces to soak up sound. The walls are double-walled steel barriers with insulation inside. The background noise in this room is -3 dB, which is 13 dB below the threshold of perfect human hearing.

Measuring Sound

There are two ways to measure sound:

• Frequency: Measures how high or low a sound is, measured in Hertz (Hz). Humans can detect sounds from 20 Hz to 20,000 Hz.

• Intensity: Measures how loud a sound is, measured in decibels (dB).

  • Human breathing: 10 dB
  • Whisper: 20 dB
  • Library: 40 dB
  • Garbage disposal: 80 dB
  • Jackhammer: 100 dB
  • Jet engine: 150 dB
  • Quietest room in the world: -3 dB

Subjectivity of Sound

Sound perception is subjective and depends on associations. A sound can be perceived as good or bad depending on the context.

Good vs. Bad Sounds (Salford University Study)

• Most Unpleasant Sounds:
  1. Human vomiting
  2. Microphone feedback
  3. Baby crying
• Most Pleasant Sounds:
  1. Friendly applause
  2. Giggly baby
  3. Thunder in the distance

Soundproofing HQ

The team applies what they learned at Orfield Labs to soundproof their HQ:

• Adding materials to the walls, including pool noodles on the window.
• Adding blankets to the walls and carpet on the ground to stop reverberations.
• Placing stuffed animals to mimic the cones in the anechoic chamber.

Embracing Good Sounds

The team realizes that the absence of sound can be unsettling and decides to incorporate "good sounds" into their podcast. They record nature sounds to use as background noise and use Mozart to relax listeners.

Conclusion

The Crafteroons team successfully soundproofs their HQ and learns to control and incorporate sound effectively. They understand the science behind sound, the importance of soundproofing, and the subjective nature of sound perception, ultimately creating a better podcasting environment.