What Does an Equalizer Actually Do?
An equalizer adjusts volume at individual frequency ranges. Music contains everything from 20 Hz to 20,000 Hz simultaneously -- the "thump" of a kick drum at 60 Hz, the body of a vocal at 300 Hz to 3 kHz, the sizzle of a cymbal at 10 kHz and above. EQ lets you raise or lower each range independently.
iPhone's built-in Music EQ (Settings > Music > EQ) offers 23 presets, but you can only choose from fixed combinations. VoicyCare's 5-band EQ gives you slider control over each band, so you can fine-tune past what presets allow. If your iPhone's volume itself feels insufficient even before EQ adjustments, our guide to breaking past iPhone's volume limit covers that separately.
One thing I want to be upfront about as the developer: EQ is not magic. It cannot restore frequencies that aren't in the original recording, and it won't turn budget earphones into premium ones. What it does is redistribute the balance of sound you already have to match your preferences and environment. Within that scope, EQ is genuinely effective.
The 5 Frequency Bands -- What Each One Controls
VoicyCare's 5-band EQ divides the spectrum into five frequency points. It's less granular than a parametric EQ used in music production, but for listening purposes it covers the ranges you'd actually want to adjust.
| Band | Frequency | Range | What Lives Here |
|---|---|---|---|
| Band 1 | ~60 Hz | Sub-bass | Kick drum thump, bass guitar fundamentals, sub-bass -- the vibration you feel physically |
| Band 2 | ~230 Hz | Low-mid | Bass lines (main range), male vocal fundamentals, cello, piano left hand |
| Band 3 | ~910 Hz | Mid | Vocal body, guitar chords, snare drum body, piano center |
| Band 4 | ~4 kHz | Upper-mid | Vocal consonants (s, t, k sounds), guitar pick attack, string overtones |
| Band 5 | ~14 kHz | Treble | Cymbal sustain, hi-hat shimmer, vocal breathiness ("air") |
When building VoicyCare, I spent time deciding where to place these five points. The 60 Hz / 230 Hz / 910 Hz / 4 kHz / 14 kHz split closely matches Apple Music's internal EQ and Spotify's 5-band layout, and it covers the frequencies that listeners most commonly want to adjust.
Understanding dB (Decibels)
EQ adjustments are measured in dB. 0 dB means no change. Positive values boost, negative values cut.
Because dB is a logarithmic scale, the numbers can be misleading:
- +3 dB = roughly 2x sound pressure. You'll notice a slight change
- +6 dB = roughly 4x sound pressure. Clearly audible difference
- +10 dB = roughly 10x sound pressure. This is usually too much
Conversely, -3 dB halves the sound pressure, -6 dB quarters it. Professional mixing engineers often follow the principle: "boost up to 3 dB, and if you need more, cut other bands instead." This "cut to raise relatively" approach avoids clipping (distortion).
Genre-Specific EQ Settings -- Starting Points
Important caveat before the settings: these are starting points, not answers. "Rock" in the 1970s (Led Zeppelin) and "rock" in the 2020s (Imagine Dragons) have completely different mixes. Play your own music and move the sliders until it sounds right to you.
Pop: Bring the Vocal Forward
In pop, the vocal is the main event. The "body" of the voice sits around 910 Hz; the "clarity" and "edge" that makes consonants cut through lives around 4 kHz. Boosting these two bands pushes the singer in front of the instruments.
| Band 1 (60 Hz) | Band 2 (230 Hz) | Band 3 (910 Hz) | Band 4 (4 kHz) | Band 5 (14 kHz) |
|---|---|---|---|---|
| 0 dB | +1 dB | +3 dB | +4 dB | +2 dB |
Keeping Band 1 at zero is deliberate -- by not boosting the bass, the vocal stands out more by contrast. If vocal consonants feel harsh (sibilant "s" sounds), drop Band 4 to +3 dB. Works across mainstream pop, indie pop, K-pop, and singer-songwriter.
Rock: The V-Curve and Why It Works
The classic rock EQ is a "V-shape" -- bass and treble up, mids slightly scooped. This emphasizes the kick drum (60 Hz) and cymbal/guitar edge (4 kHz-14 kHz) while pulling back the congested midrange where vocals and guitars compete for space.
| Band 1 (60 Hz) | Band 2 (230 Hz) | Band 3 (910 Hz) | Band 4 (4 kHz) | Band 5 (14 kHz) |
|---|---|---|---|---|
| +4 dB | +2 dB | -1 dB | +3 dB | +4 dB |
For heavier subgenres (metal, hard rock), try pushing Band 1 to +5 or +6 dB. If your earphones distort at those levels, try cutting Band 3 to -2 dB instead -- cutting the mids makes the bass more prominent without actually boosting it, which avoids clipping.
Classical: Flat Is the Point
Classical recordings are engineered to capture the hall acoustics as a single unified soundscape. The recording engineer has already set the balance. Heavy EQ changes break the spatial relationships and make the recording sound unnatural.
| Band 1 (60 Hz) | Band 2 (230 Hz) | Band 3 (910 Hz) | Band 4 (4 kHz) | Band 5 (14 kHz) |
|---|---|---|---|---|
| 0 dB | 0 dB | 0 dB | +1 dB | +2 dB |
The tiny Band 4/5 lift adds a hint of "air" for flute and violin harmonics when listening through earphones. Many people find completely flat (all 0 dB) to be the best setting for classical. Don't exceed +3 dB on any band.
Jazz: Upright Bass and Cymbal Shimmer
The two defining textures of jazz: the round "thud" of an upright bass (230 Hz) and the delicate sizzle of brushes on a ride cymbal (14 kHz). Bringing both out simultaneously creates a club-like intimacy.
| Band 1 (60 Hz) | Band 2 (230 Hz) | Band 3 (910 Hz) | Band 4 (4 kHz) | Band 5 (14 kHz) |
|---|---|---|---|---|
| +2 dB | +3 dB | 0 dB | +2 dB | +4 dB |
For vocal jazz, add +2 dB to Band 3 to bring the singer forward. If you want a fatter saxophone tone, try Band 2 at +4 dB. Works for bebop, cool jazz, smooth jazz, and Latin jazz.
EDM / Dance: Bass Power, but Watch the Limits
EDM kicks and bass drops concentrate in the 50-100 Hz range, so Band 1 boost is directly effective. But +6 dB is serious amplification (4x sound pressure). On small earphone drivers like AirPods, the physical limits of the driver can cause distortion before you get the bass impact you want.
| Band 1 (60 Hz) | Band 2 (230 Hz) | Band 3 (910 Hz) | Band 4 (4 kHz) | Band 5 (14 kHz) |
|---|---|---|---|---|
| +6 dB | +4 dB | 0 dB | +1 dB | +3 dB |
If you hear distortion, drop Band 1 to +4 dB. Alternatively, cut Band 3 to -2 dB to make the bass more prominent by contrast -- this is cleaner. Band 5 at +3 dB keeps synth leads and hi-hats bright. Works for house, techno, trance, dubstep, and drum and bass.
R&B / Soul: Smooth and Warm
R&B blends vocal performance with groove-driven bass. The EQ should support the voice while keeping the low end smooth and full.
| Band 1 (60 Hz) | Band 2 (230 Hz) | Band 3 (910 Hz) | Band 4 (4 kHz) | Band 5 (14 kHz) |
|---|---|---|---|---|
| +3 dB | +2 dB | +3 dB | +2 dB | +1 dB |
A gentle, rounded boost across most bands creates enveloping warmth without any single frequency dominating. Also works well for hip-hop and neo-soul.
Scene-Based EQ Settings
The best EQ depends not just on the genre, but on where and how you're listening. I tested various scenarios during VoicyCare's development -- these settings had the most impact.
Commuting (Train/Bus Noise)
Train rumble concentrates in the 80-250 Hz range. Boosting bass to compete with it just amplifies the noise along with the music. The more effective approach is counterintuitive: raise the mids and highs instead, and cut the lows.
| Band 1 (60 Hz) | Band 2 (230 Hz) | Band 3 (910 Hz) | Band 4 (4 kHz) | Band 5 (14 kHz) |
|---|---|---|---|---|
| -2 dB | -1 dB | +3 dB | +4 dB | +2 dB |
Cutting the low end reduces overlap with ambient noise, while boosting vocal and attack frequencies makes music cut through. If you have noise-canceling earphones, you won't need such extreme adjustments. For Bluetooth-specific volume issues that affect EQ perception, see our AirPods and Bluetooth volume boost guide.
Podcasts and Audiobooks (Voice Clarity)
Voice-only content has a simple EQ strategy: boost the 2-4 kHz clarity range and cut the low-end rumble.
| Band 1 (60 Hz) | Band 2 (230 Hz) | Band 3 (910 Hz) | Band 4 (4 kHz) | Band 5 (14 kHz) |
|---|---|---|---|---|
| -3 dB | -1 dB | +2 dB | +4 dB | 0 dB |
Band 5 stays at 0 dB because podcasts have almost nothing at 14 kHz -- boosting it only amplifies microphone hiss and sibilance. Cutting Band 1 to -3 dB also reduces plosive pops ("p" and "b" sounds) and ambient low-frequency rumble.
EQ for Hearing Loss Compensation
EQ was designed to adjust music balance, but it's also useful for compensating for frequencies you can't hear as well. Boosting only the frequencies you need is safer than raising overall volume.
Age-Related Hearing Loss (High-Frequency)
Age-related hearing loss (presbycusis) almost always starts above 4 kHz. Vocal consonants ("s", "t", "th"), cymbals, and string harmonics become muffled. Selectively boosting Band 4 and Band 5 targets exactly what's been lost.
| Band 1 (60 Hz) | Band 2 (230 Hz) | Band 3 (910 Hz) | Band 4 (4 kHz) | Band 5 (14 kHz) |
|---|---|---|---|---|
| 0 dB | 0 dB | +2 dB | +5 dB | +6 dB |
This is fundamentally the same thing hearing aids do -- targeted amplification rather than blanket volume increase. EQ can help with mild to moderate loss, but it's not a substitute for professional hearing care in more severe cases. VoicyCare's EQ won't replace a hearing aid, but for "things are getting a bit harder to hear" it makes a real difference.
Low-Frequency Hearing Loss
Less common, but it occurs with some types of conductive hearing loss. Boost Band 1 and Band 2 to restore the musical foundation.
| Band 1 (60 Hz) | Band 2 (230 Hz) | Band 3 (910 Hz) | Band 4 (4 kHz) | Band 5 (14 kHz) |
|---|---|---|---|---|
| +6 dB | +4 dB | +1 dB | 0 dB | 0 dB |
Note that 60 Hz boost effectiveness depends on your earphone driver size. Small earphones physically can't reproduce deep bass, so EQ can only do so much.
Using VoicyCare's Presets
VoicyCare includes a "Clear" preset that boosts high frequencies with a single tap -- no manual dB adjustment needed. Start there, then tweak individual bands. Combined with VoicyCare's 200% volume amplification, you can improve clarity at safe listening levels. Volume increase and EQ compensation are separate approaches, and they work better together. For a broader look at volume booster options, see our best free volume booster apps comparison.
Setting Up VoicyCare's Equalizer
- Open the app: Launch VoicyCare and select a song
- Go to EQ: Tap the EQ icon at the bottom of the screen
- Try a preset: "Flat," "Clear," or "Bass Boost." Even just this makes a noticeable difference
- Adjust sliders: Drag bands up or down while music plays -- changes are audible in real time
- Settings auto-save: Your adjustments persist -- no need to reconfigure each time
Three Common EQ Mistakes
1. Boosting All Bands
Setting all five sliders to +6 dB doesn't reshape anything -- it just raises overall volume while eating into digital headroom. The combined signals exceed what the output can handle and you get clipping (harsh distortion). EQ is for changing balance, not volume. Use the volume slider for volume.
2. Extreme Boosts (+10 dB or Higher)
+10 dB is approximately 10x sound pressure. At that level, the boosted band drowns out everything else and likely exceeds your earphone driver's capabilities, causing distortion. My personal rule: if you're tempted to go above +6 dB, stop and ask whether cutting other bands would achieve the same effect more cleanly.
3. Only Boosting, Never Cutting
In music production, the principle is "cut to clean up, boost to flavor." If you want vocals to stand out, cutting Band 1 by -3 dB achieves a similar effect to boosting Band 3 by +4 dB -- except cutting carries less risk of clipping and produces cleaner results. Try pulling bands down before pushing them up.
What EQ Cannot Do
I've covered what EQ can do. Here's what it honestly cannot:
- Recover lost recording quality: High frequencies stripped by low-bitrate MP3 compression are gone. Boosting that range amplifies nothing -- the data isn't there
- Overcome hardware limits: If your earphone's driver physically can't reproduce 60 Hz (common in small earbuds), no amount of EQ boost will create bass that the hardware can't output. It will just distort
- Change stereo image or spatial positioning: EQ adjusts frequency balance. It doesn't affect width, depth, or instrument placement in the stereo field
- Boost signal without boosting noise: When you raise a frequency band, any noise in that band gets louder too. This is why cutting is often cleaner than boosting
EQ redistributes what you already have. Don't expect miracles, but do use it actively to match your preferences and environment.
Try VoicyCare's Equalizer
5-band EQ, 200% volume amplification, preset modes. No ads, no subscriptions. Enter the dB values from this article and hear the difference for yourself.
Download for FreeSummary
- EQ basics: 5-band EQ adjusts volume across frequency ranges. +3 dB roughly doubles sound pressure
- Pop: Boost Band 3 and 4 for vocal body and clarity
- Rock: V-curve -- bass and treble up, mids slightly scooped for separation
- Classical: Flat. At most +1-2 dB treble lift
- Jazz: Band 2 and 5 for upright bass and cymbal shimmer
- EDM: Band 1 at +4-6 dB. If earphones distort, back off
- R&B/Soul: Gentle rounded boost for warmth
- Commuting: Cut lows, boost mids and highs to cut through ambient noise
- Hearing loss: Age-related: boost Band 4 and 5. "Clear" preset is a quick start
- Avoid: Boosting all bands, exceeding +10 dB, only boosting and never cutting
These settings are starting points. Play your own music, move the sliders, and find the spot that sounds right. That's the real value of an equalizer.