⚙️ ENGINEER LEVEL: Technical Terminology

Acoustic Impedance (Z_acoustic): Ratio of sound pressure to particle velocity in medium. For air: ρc ≈ 415 rayls.

Acoustic Center: Apparent point source of sound radiation from speaker. Important for time alignment.

Acoustic Power: Sound energy radiated per unit time, measured in watts. Different from electrical power.

Amplitude Modulation (AM): Variation of signal amplitude. Can be distortion product in poorly designed systems.

Anechoic: Environment with no reflections. Required for accurate speaker measurements.

Audibility Threshold: Minimum detectable change in level, frequency, or timing. Varies with frequency and level.

Back-EMF (Electromotive Force): Voltage generated by voice coil motion through magnetic field. Provides electrical damping.

Bandwidth: Frequency range over which device operates. May be limited by -3dB points.

Baffle: Surface on which speaker is mounted. Affects low-frequency response.

Bessel Function: Mathematical function describing diffraction patterns. Relevant for horn and waveguide design.

Butterworth Alignment: Crossover or enclosure response with maximally flat passband. Q = 0.707.

Chebyshev Alignment: Response with ripple in passband but steeper rolloff than Butterworth.

Comb Filtering: Interference pattern creating series of peaks and nulls. Caused by reflections or multiple drivers.

Complex Impedance: Impedance with resistive and reactive (inductive/capacitive) components. Z = R + jX.

Critical Damping: Damping level where system returns to equilibrium without oscillation. Q = 0.5.

Crossover Distortion: Non-linearity in Class AB amplifiers at zero-crossing point.

Diffraction: Bending of sound waves around obstacles. Affects speaker response.

Dispersion: Angular distribution of sound radiation from speaker.

Doppler Distortion: Frequency modulation caused by cone motion. Relevant when single driver reproduces wide frequency range.

Dynamic Range: Ratio between loudest and quietest sounds system can reproduce.

Enclosure Loss: Acoustic power absorbed by enclosure walls and damping material.

Equal-Loudness Contour (Fletcher-Munson): Curves showing SPL required for equal perceived loudness at different frequencies.

Far-Field: Distance where speaker behaves as point source. Typically >3× largest dimension.

Force Factor (Bl): Product of magnetic flux density and conductor length. Determines motor strength.

Free-Field Response: Speaker response measured without reflections.

Group Delay: Frequency-dependent delay through system. Can cause smearing if excessive.

Haas Effect (Precedence Effect): First arriving sound determines perceived direction, even if later arrival is louder.

Helmholtz Resonance: Resonance of air mass in port coupled to enclosure volume.

Impulse Response: System output to instantaneous pulse. Reveals all frequency and time behavior.

Inductor (Coil): Component that opposes changes in current. Used in passive crossovers and Class D output filters.

Intermodulation Distortion (IMD): Distortion creating sum and difference frequencies of input tones.

Linkwitz-Riley Alignment: Crossover where drivers sum to flat response. 4th order: Q = 0.707 per driver.

Lorentz Force: Force on current-carrying conductor in magnetic field. F = Bl × I.

Lumped-Parameter Model: Simplification where distributed properties treated as discrete components.

Masking: Phenomenon where loud sound makes nearby frequencies/times inaudible.

Maximum Length Sequence (MLS): Pseudo-random signal for fast system measurement.

Minimum Phase: System where magnitude and phase responses are uniquely related via Hilbert transform.

Near-Field: Region close to speaker where response is complex. Not suitable for measurement.

Nonlinear Distortion: Distortion caused by non-proportional input/output relationship.

Passive Radiator: Unpowered driver that resonates in enclosure. Alternative to port.

Phase Response: Phase shift vs. frequency. Affects transient reproduction.

Pink Noise: Random noise with constant energy per octave. Useful for system analysis.

Power Compression: SPL loss due to voice coil heating increasing resistance.

Psychoacoustics: Study of sound perception. Explains why measurements don't fully predict perception.

Radiation Impedance: Acoustic load presented by air to vibrating surface. Frequency dependent.

Reactance: Imaginary component of impedance. Caused by inductance and capacitance.

Resonance: Frequency where system naturally vibrates with minimal damping. Characterized by Q.

Ripple: Small variations in frequency response. Typically measured peak-to-peak.

Room Modes: Standing waves at specific frequencies determined by room dimensions.

Slew Rate: Maximum rate of change of output voltage. dV/dt in V/μs. Limiting causes TIM distortion.

Spectral Decay (Waterfall Plot): 3D plot showing frequency response vs. time. Reveals resonances and decay behavior.

Standing Wave: Stationary interference pattern from forward and reflected waves.

Step Response: Output to instantaneous step change in input. Related to impulse response by integration.

Subsonic: Frequencies below hearing range (<20 Hz). Can damage speakers without producing audible output.

Suspension Compliance (Cms): Flexibility of speaker surround and spider. Measured in meters/Newton.

Transfer Function: Mathematical relationship between input and output. H(s) = Output(s) / Input(s).

Transient Response: System behavior with rapidly changing signals. Important for accurate reproduction.

Transmission Line: Enclosure design using long, damped cavity. Quarter-wave resonance extends bass.

Voice Coil Inductance (Le): Inductance of voice coil. Increases impedance at high frequencies. Reduces damping.

White Noise: Random noise with constant energy per Hz. Useful for testing but sounds harsh.

Zobel Network: Series RC circuit that flattens impedance rise from voice coil inductance.

END OF CHAPTER 1

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