When you look at headphone or speaker specs, you’ll see numbers like “32Ω” (ohms) or “98dB/mW” (decibels per milliwatt). These aren’t random—they’re impedance and sensitivity, two key parameters that determine if your audio gear will work with your devices (e.g., phone, laptop, amplifier) and how loud/clear it will sound.
We’ve seen customers make costly mistakes: Buying 300Ω headphones for their phone (the phone can’t “push” enough power, so sound is quiet and muddy). Or choosing a low-sensitivity speaker (85dB/mW) for their living room (it needs to be cranked to fill the space, causing distortion). Understanding impedance and sensitivity doesn’t require math—just a basic grasp of what they do. Let’s break them down, how to read them, and how to pick the right specs for your setup.
First: What Is Impedance? (The “Resistance” of Audio Gear)
Impedance (measured in ohms, Ω) is how much an audio device resists electrical current from your播放设备 (phone, amplifier). Think of it like a water hose: Low impedance (narrow hose) lets more water (power) flow through; high impedance (wide hose) needs more pressure (power) to flow.
For audio gear, impedance determines if your播放设备 can “drive” the device (make it sound loud enough):
| Impedance Range | What It Means | Best Playback Device | Common Devices |
|---|---|---|---|
| Low (16–32Ω) | Easy to drive—needs little power. | Phones, laptops, tablets (low-power devices). | Most consumer headphones (in-ear, budget over-ear), portable speakers. |
| Medium (40–100Ω) | Needs more power—works with most devices but sounds better with a dedicated amplifier. | Phones (at max volume), portable music players (e.g., Sony Walkman), small amplifiers. | Mid-range over-ear headphones, bookshelf speakers. |
| High (150–600Ω) | Requires a lot of power—won’t work well with phones. | Dedicated amplifiers, home theater receivers. | Professional headphones (e.g., Sennheiser HD 650), studio monitors. |
Critical Example: A 32Ω in-ear headphone works great with a phone—you can hear it at 50% volume. A 300Ω professional headphone connected to the same phone will be quiet even at 100% volume, and bass will be weak (the phone can’t push enough power).
Second: What Is Sensitivity? (How Loud a Device Gets)
Sensitivity (measured in dB/mW or dB/V) tells you how loud a device gets with a given amount of power. Higher sensitivity = louder sound at the same power level.
For example:
- A headphone with 98dB/mW will be louder than one with 90dB/mW when connected to the same phone (both 32Ω).
- Sensitivity is more important than impedance for volume—even a low-impedance headphone with low sensitivity will be quiet.
| Sensitivity Range | What It Means | Best For | |
|---|---|---|---|
| Low (85–90dB/mW) | Quiet—needs more power to get loud. | Home speakers (paired with amplifiers). | Large floor-standing speakers, studio monitors. |
| Medium (91–95dB/mW) | Balanced—loud enough for most devices. | Everyday headphones, portable speakers. | In-ear buds, budget over-ear headphones. |
| High (96–110dB/mW) | Very loud—works with low-power devices. | Commute headphones, small speakers. | Sports headphones, tiny portable speakers. |
Pro Tip: For commuters, look for sensitivity ≥95dB/mW—you’ll hear music clearly over subway noise without cranking volume to unsafe levels (≥85dB for 8+ hours can damage hearing).
How to Pick the Right Impedance & Sensitivity for Your Gear
The key is to match your audio device’s specs to your播放设备. Here’s a simple guide:
1. If You Use a Phone/Laptop (Low-Power Devices)
- Headphones: Choose 16–32Ω impedance + 95–100dB/mW sensitivity. Examples: Apple AirPods (20Ω, 99dB/mW), Sony WF-C500 (16Ω, 95dB/mW).
- Speakers: Choose ≤8Ω impedance + 88–92dB/mW sensitivity. Examples: Portable Bluetooth speakers (4Ω, 90dB/mW).
2. If You Use a Portable Music Player (Mid-Power Devices)
- Headphones: 32–60Ω impedance + 92–96dB/mW sensitivity. Examples: Sony WH-1000XM5 (32Ω, 94dB/mW).
- Speakers: 8–16Ω impedance + 90–94dB/mW sensitivity. Examples: Bookshelf speakers (8Ω, 92dB/mW).
3. If You Use an Amplifier/Receiver (High-Power Devices)
- Headphones: 150–300Ω impedance + 90–94dB/mW sensitivity. Examples: Sennheiser HD 650 (300Ω, 97dB/mW).
- Speakers: 8–16Ω impedance + 92–96dB/mW sensitivity. Examples: Floor-standing speakers (8Ω, 94dB/mW).
Common Myths to Bust
- Myth: “High impedance = better sound.” Truth: Impedance affects power needs, not sound quality. A 32Ω headphone can sound just as good as a 300Ω one if it’s well-designed.
- Myth: “Sensitivity doesn’t matter if impedance is low.” Truth: A 32Ω headphone with 85dB/mW will be quieter than a 32Ω headphone with 98dB/mW—sensitivity determines volume.
How to Check Your Device’s Power Output
If you’re unsure if your phone can drive a headphone, check its “output power” (usually listed in mW):
- Phones: 5–10mW (can drive 16–32Ω headphones).
- Portable players: 10–20mW (can drive 32–60Ω headphones).
- Amplifiers: 50–100mW (can drive 150–300Ω headphones).
Example: A customer’s phone outputs 8mW—they bought 300Ω headphones and wondered why they were quiet. Switching to 32Ω headphones (98dB/mW) fixed the issue—sound was loud and clear at 50% volume.
