Reading Frequency Response Graphs

Frequency response graphs are one of the most important measurements in audio, showing how a speaker or headphone reproduces different frequencies. Learning to read these graphs helps you make informed purchasing decisions and understand your equipment's strengths and weaknesses.

For consistent spoken-word references while comparing plots, generate neutral narration with VoiceForge and feed the playback through your monitors as you analyze each measurement.

What is a Frequency Response Graph?

A frequency response graph plots frequency (Hz) on the horizontal X-axis and amplitude (dB) on the vertical Y-axis. It shows how loud each frequency is relative to a reference level.

Key Components

X-axis (horizontal): Frequency from 20 Hz (bass) to 20,000 Hz (treble). Usually logarithmic scale.
Y-axis (vertical): Loudness in decibels (dB). Shows relative output level.
The line: Shows how much output at each frequency. Flat = accurate, peaks = louder, dips = quieter.
0 dB reference: Baseline. +3 dB = twice as loud, -3 dB = half as loud (approximately).

Reading the Graph

Flat Response = Accurate

Ideally, the line should be relatively flat (within ±3 dB) from 20 Hz to 20 kHz. This means all frequencies are reproduced at equal volume, giving accurate, uncolored sound.

Peaks (Humps) = Emphasis

When the line goes above the reference, that frequency is louder:

Bass peak (40-80 Hz): "Boomy" or "warm" sound
Midrange peak (1-3 kHz): "Forward" or "aggressive" presentation
Treble peak (8-10 kHz): "Bright" or "sibilant" sound

Dips (Valleys) = Recession

When the line goes below the reference, that frequency is quieter:

Bass dip: "Thin" or "lacking body"
Midrange dip: "Distant" or "recessed" vocals
Treble dip: "Dull" or "muffled" sound

Roll-Off = Frequency Limits

When the line slopes downward at the extremes, the speaker can't reproduce those frequencies. Most speakers roll off below 40-60 Hz (bass) and above 18-20 kHz (treble). This is normal and expected.

Common Frequency Response Patterns

"V-Shaped" Response

Pattern: Boosted bass and treble, recessed midrange
Sound: "Fun," "exciting," good for casual listening and bass-heavy music
Common in: Consumer headphones, Bluetooth speakers

"Studio Monitor" Response

Pattern: Flat across the spectrum
Sound: Accurate, neutral, "boring" to some listeners
Common in: Professional monitors, reference headphones

"Bright" Response

Pattern: Elevated treble above 4 kHz
Sound: "Detailed," "airy," but can be fatiguing
Common in: Some hi-fi speakers, analytical headphones

"Warm" Response

Pattern: Elevated bass, rolled-off treble
Sound: "Rich," "smooth," less detail
Common in: Vintage speakers, "musicality-focused" gear

What to Look For

Good Frequency Response Characteristics

Smooth curve: Gradual changes, not jagged or erratic
Within ±3 dB: From 100 Hz to 10 kHz (most audible range)
Extended bass: Flat response down to at least 40-50 Hz (full-range speakers)
Extended treble: Flat to 15-18 kHz minimum
No severe dips: Especially in midrange (500 Hz - 4 kHz)

Limitations and Caveats

Frequency Response Doesn't Tell Everything

Doesn't show distortion: A speaker can be flat but distorted
Doesn't show timing: Phase response and group delay matter too
Measurement conditions vary: On-axis vs. off-axis, anechoic vs. in-room
Subjective preferences differ: Some people prefer colored sound
Room affects final sound: Your room will alter the response significantly

Testing Your Own Equipment

While professional measurement equipment is expensive, you can get a sense of your speaker's frequency response using AudioTest Pro:

DIY Frequency Response Test

Use the Precision Tone Generator
Set volume to comfortable level at 1 kHz
Play test tones at: 40 Hz, 63 Hz, 100 Hz, 250 Hz, 500 Hz, 1 kHz, 2 kHz, 4 kHz, 8 kHz, 12 kHz, 16 kHz
Note which frequencies sound louder or quieter than 1 kHz reference
This gives you a rough idea of your system's frequency balance

Key Takeaways

Frequency response shows how evenly a speaker reproduces different frequencies
Flatter is generally better for accuracy, but preferences vary
Look for smooth curves within ±3 dB from 100 Hz to 10 kHz
Peaks = emphasis, dips = recession, roll-off = frequency limits
Frequency response is important but not the whole story
Your room will affect the final sound you hear