🔰 BEGINNER LEVEL: Sound Basics
What is Sound?
Sound is vibration traveling through air (or another medium). When something vibrates - a speaker cone, guitar string, or your vocal cords - it pushes and pulls air molecules, creating pressure waves that travel to your ears.
Simple analogy: Think of dropping a pebble in a pond. The ripples spreading outward are similar to sound waves spreading through air.
Key properties of sound: 1. Frequency: How fast it vibrates (measured in Hz - cycles per second) - Low frequency = low pitch (bass, rumble) - High frequency = high pitch (treble, sparkle) - Humans hear roughly 20 Hz to 20,000 Hz (20 kHz)
Amplitude: How much it moves (measured in dB - decibels)
- Higher amplitude = louder sound
- Lower amplitude = quieter sound
Phase: The timing of the wave
- In phase = waves align and add together
- Out of phase = waves cancel each other
What are Decibels (dB)?
Decibels are a way to measure sound intensity. The decibel scale is logarithmic, not linear - this is confusing at first but important to understand.
Why logarithmic? - Human hearing perceives sound logarithmically - Sound power can vary by trillions of times (quiet whisper to jet engine) - Logarithmic scale compresses huge range into manageable numbers
Key reference points:
| Decibel Level | Example | Experience |
|---|---|---|
| 0 dB | Absolute silence | Threshold of hearing |
| 30 dB | Quiet library | Very quiet |
| 60 dB | Normal conversation | Comfortable |
| 85 dB | City traffic | Hearing damage risk starts |
| 100 dB | Nightclub, chainsaw | Temporary threshold shift |
| 120 dB | Rock concert, loud car audio | Painful |
| 140 dB | Gunshot, jet engine | Immediate hearing damage |
| 150 dB | Competition car audio | Extreme SPL, earplugs required |
Important facts: - +3 dB = doubling of power (but doesn't sound twice as loud) - +10 dB = 10x power, perceived as "twice as loud" - Every +10 dB = 10x the power - +20 dB = 100x power, perceived as "four times as loud"
Example: - 90 dB requires 100 watts - 93 dB requires 200 watts (+3 dB) - 100 dB requires 1,000 watts (+10 dB) - 110 dB requires 10,000 watts (+20 dB)
This is why chasing extreme SPL is expensive - every 3 dB doubles your power requirements!
Hearing Protection
Exposure time limits: - 85 dB: 8 hours maximum daily exposure - 88 dB: 4 hours - 91 dB: 2 hours - 94 dB: 1 hour - 97 dB: 30 minutes - 100 dB: 15 minutes
For competition SPL systems (140-150+ dB): - ALWAYS wear hearing protection - Use rated earplugs or earmuffs - Exposure time: seconds only - Permanent hearing damage occurs immediately without protection