{"course":{"slug":"motion-and-audio","title":"Motion, Sound and Music","url":"https://addaly.com/learn/motion-and-audio","level":"intermediate","track":"create"},"lesson":{"slug":"small-speakers-and-translation","title":"What survives a phone speaker","url":"https://addaly.com/learn/motion-and-audio/small-speakers-and-translation","position":62,"of":72,"minutes":10,"answer":"A phone speaker produces little below 500 to 700Hz, so bass is inferred from its harmonics through the missing-fundamental effect and a pure sine sub disappears entirely, which is why the 1 to 4kHz band.","keyIdea":"A phone speaker produces little below 500 to 700Hz, so bass is inferred from its harmonics through the missing-fundamental effect and a pure sine sub disappears entirely, which is why the 1 to 4kHz band, where intelligibility lives, is the one that has to be right."},"body":{"format":"markdown","text":"## Your mix will be heard on something worse than what you mixed on\n\nA phone speaker is a few millimetres across and sealed into a case. Its useful output typically begins somewhere around **500 to 700Hz** and falls away sharply below that. A laptop speaker does a little better, often reaching 200 to 300Hz. A pair of earbuds and a decent television soundbar do better still.\n\nWhatever you mixed on, a substantial share of your audience will hear your work through one of those. Nothing below the speaker's limit exists for them: the bass is not quiet, it is absent.\n\n## The missing fundamental\n\nPlay a 100Hz note on a phone speaker and you will still perceive the pitch, even though the speaker cannot produce 100Hz.\n\n> Figure: Where each speaker stops producing bass. Bars (Hz, lowest useful output): Phone speaker 600; Laptop speaker 250; Earbuds 90; Television soundbar 60. Below its limit a speaker produces nothing at all: the bass is not quiet, it is absent. A pitch can still be heard from its harmonics through the missing-fundamental effect, which is why a pure sine sub disappears on a phone and a saturated bass does not. The band from 1 to 4 kHz survives every system and carries intelligibility, which is where the care belongs.\n\nThe reason is that a real sound at 100Hz is accompanied by harmonics at 200, 300, 400Hz and up. Those harmonics do come through, and the auditory system infers the fundamental from the spacing between them. This is the **missing fundamental** effect, and it is why a small speaker can convey a bass line at all.\n\nTwo consequences for mixing:\n\n- **A pure sine sub-bass disappears entirely** on a small speaker, because it has no harmonics to infer from. If low-end content matters, it needs harmonic content above 500Hz, which is what saturation and distortion on a bass are actually for.\n- **Low-frequency energy you cannot hear on a phone is still in the file**, eating headroom in the limiter and making the mix quieter after normalisation. This is the practical argument for high-passing everything that does not need low end, not just the voice.\n\n## What survives, and what to protect\n\nThe range from about **1 to 4kHz** survives every playback system and carries speech intelligibility. If the mix works there, it works everywhere. If the mix depends on anything below 300Hz to sound full, it will sound thin to most of your audience.\n\nThis tells you where to spend care: consonant clarity, the relationship between dialogue and everything else in the midrange, and whether the music bed is competing in that band.\n\n## Checking, in three steps\n\n**1. A phone speaker, at arm's length, at low volume.** Not earbuds: the built-in speaker. This is the most brutal and most representative test available, and it costs nothing. Listen for: can you follow the words, does the music vanish or dominate, is anything unpleasantly harsh.\n\n**2. Mono.** Covered in the capture module for phase reasons, and it applies again here because most small speakers are single. One click.\n\n**3. Quietly.** Equal-loudness contours mean the ear is far less sensitive to bass and treble at low levels than in the middle. A mix balanced at a comfortable monitoring level will sound midrange-heavy when quiet, and most listening is quiet. Mixing at moderate to low levels most of the time produces mixes that translate better, and it protects your hearing, which is the other reason to do it.\n\n## Reference tracks\n\nThe most reliable single technique: import two or three professionally finished pieces in the same genre, level-matched to your mix, and switch between them.\n\nLevel-matching is the step people skip and it invalidates the comparison if you skip it: louder sounds better, so an unmatched reference always wins or always loses for the wrong reason. Match by integrated LUFS using the meter from the loudness lesson, then compare.\n\nListen for the relationships rather than the tone: how loud is the voice against the music, how much low end is there, how bright are the consonants. You are checking your decisions against people who had better rooms and better monitoring.\n\n## Your room is lying to you\n\nEvery domestic room has strong low-frequency modes: peaks and nulls of 10dB or more at specific frequencies, determined by its dimensions. If your listening position sits in a null at 80Hz, you will add bass to compensate and your mix will be bass-heavy everywhere else. If it sits in a peak, the opposite.\n\nTwo cheap mitigations. **Headphones** have no room, and while they misrepresent stereo width and bass extension in their own ways, they are consistent, and a known error is more useful than an unknown one. **Multiple systems** average out individual errors: monitors, headphones, a laptop, a phone, the car. Anything that sounds right on four different systems is right.\n\n## The free path\n\nEverything here is free. A phone you already own, headphones you already own, **ffmpeg** or any editor for level-matched references, and a mono button. **REW** measures your room's frequency response at the listening position for the cost of a measurement microphone, and even a rough measurement tells you where the big dips are.\n\n## The limitation\n\nTranslation checking tells you what is wrong and not what to do about it. A mix that sounds thin on a phone might need more midrange, less low end, a different arrangement, or nothing at all, because some material cannot survive a phone speaker and pretending otherwise ruins it everywhere else.\n\nThere is also no such thing as a mix that is optimal on every system. Decisions that help a phone (more midrange, controlled dynamics, less sub) cost something on a good system. Professional practice is to mix for the primary listening context and check that nothing breaks elsewhere, rather than to average across all of them and satisfy none."},"check":{"question":"A mix contains a deep sine-wave sub under a title sequence. It is clearly audible on monitors and completely absent on a phone, while a bass guitar in the same register comes through as a recognisable pitch. What explains the difference?","options":[{"text":"The bass guitar is louder in the mix at those frequencies, and the phone speaker has a steep enough roll-off that a few decibels of level determines whether content crosses its threshold.","correct":false,"tempting":"Reasons from level, when the difference is that one sound has harmonics and the other does not."},{"text":"The phone's playback chain applies dynamic range compression that boosts quiet low-frequency content, and a sustained sine is treated as noise by the gate in that processing.","correct":false,"tempting":"Invents a specific processing behaviour; the mechanism is in the speaker's response and the listener's hearing."},{"text":"The bass guitar's harmonics at 200Hz and above do reach the speaker, and the ear infers the fundamental from their spacing; the sine has no harmonics to infer from.","correct":true},{"text":"The sine is a single frequency and therefore excites only one point on the speaker's diaphragm, while the guitar's broadband content excites the whole surface and produces enough total displacement to be audible even below the speaker's rated response.","correct":false,"tempting":"Describes speaker behaviour in terms that do not correspond to how a diaphragm radiates; the explanation lies in the harmonic structure of the source."}]},"prev":{"slug":"loudness-and-lufs","title":"The number every platform measures","url":"https://addaly.com/learn/motion-and-audio/loudness-and-lufs"},"next":{"slug":"the-order-of-operations","title":"The chain, and why the order is not arbitrary","url":"https://addaly.com/learn/motion-and-audio/the-order-of-operations"},"authorship":"Founder and series editor: Dr Mustafa Mun. Written by AI models to a written standard. Exam keys checked blind by a second model: 3,665 of 3,666 agreed. Academic review invited.","review":{"status":"Draft, open for academic review"},"cite":"Addaly (2026) 'What survives a phone speaker', in Motion, Sound and Music. Edited by M. Mun. Addaly. Available at: https://addaly.com/learn/motion-and-audio/small-speakers-and-translation (Accessed: 13 October 2026).","licence":{"name":"CC BY-NC-SA 4.0","url":"https://creativecommons.org/licenses/by-nc-sa/4.0/"},"reader":{"schema":1,"title":"What survives a phone speaker","courseTitle":"Motion, Sound and Music","module":{"index":7,"slug":"shaping-and-mixing-sound","title":"Shaping and mixing sound"},"answer":null,"keyIdea":"A phone speaker produces little below 500 to 700Hz, so bass is inferred from its harmonics through the missing-fundamental effect and a pure sine sub disappears entirely, which is why the 1 to 4kHz band, where intelligibility lives, is the one that has to be right.","hero":{"kind":"figure","figure":{"t":"figure","label":"Figure","figure":{"type":"bars","unit":"Hz, lowest useful output","title":"Where each speaker stops producing bass","series":[{"label":"Phone speaker","value":600,"highlight":true},{"label":"Laptop speaker","value":250},{"label":"Earbuds","value":90},{"label":"Television soundbar","value":60}],"caption":"Below its limit a speaker produces nothing at all: the bass is not quiet, it is absent. A pitch can still be heard from its harmonics through the missing-fundamental effect, which is why a pure sine sub disappears on a phone and a saturated bass does not. The band from 1 to 4 kHz survives every system and carries intelligibility, which is where the care belongs."},"alt":"Figure: Where each speaker stops producing bass. Bars (Hz, lowest useful output): Phone speaker 600; Laptop speaker 250; Earbuds 90; Television soundbar 60. Below its limit a speaker produces nothing at all: the bass is not quiet, it is absent. A pitch can still be heard from its harmonics through the missing-fundamental effect, which is why a pure sine sub disappears on a phone and a saturated bass does not. The band from 1 to 4 kHz survives every system and carries intelligibility, which is where the care belongs."}},"blocks":[{"t":"h2","id":"your-mix-will-be-heard-on-something-worse-than-what-you-mixe","runs":[{"text":"Your mix will be heard on something worse than what you mixed on"}]},{"t":"p","runs":[{"text":"A phone speaker is a few millimetres across and sealed into a case. Its useful output typically begins somewhere around "},{"text":"500 to 700Hz","b":true},{"text":" and falls away sharply below that. A laptop speaker does a little better, often reaching 200 to 300Hz. A pair of earbuds and a decent television soundbar do better still."}]},{"t":"p","runs":[{"text":"Whatever you mixed on, a substantial share of your audience will hear your work through one of those. Nothing below the speaker’s limit exists for them: the bass is not quiet, it is absent."}]},{"t":"h2","id":"the-missing-fundamental","runs":[{"text":"The missing fundamental"}]},{"t":"p","runs":[{"text":"Play a 100Hz note on a phone speaker and you will still perceive the pitch, even though the speaker cannot produce 100Hz."}]},{"t":"p","runs":[{"text":"The reason is that a real sound at 100Hz is accompanied by harmonics at 200, 300, 400Hz and up. Those harmonics do come through, and the auditory system infers the fundamental from the spacing between them. This is the "},{"text":"missing fundamental","b":true},{"text":" effect, and it is why a small speaker can convey a bass line at all."}]},{"t":"p","runs":[{"text":"Two consequences for mixing:"}]},{"t":"ul","items":[[{"text":"A pure sine sub-bass disappears entirely","b":true},{"text":" on a small speaker, because it has no harmonics to infer from. If low-end content matters, it needs harmonic content above 500Hz, which is what saturation and distortion on a bass are actually for."}],[{"text":"Low-frequency energy you cannot hear on a phone is still in the file","b":true},{"text":", eating headroom in the limiter and making the mix quieter after normalisation. This is the practical argument for high-passing everything that does not need low end, not just the voice."}]]},{"t":"h2","id":"what-survives-and-what-to-protect","runs":[{"text":"What survives, and what to protect"}]},{"t":"p","runs":[{"text":"The range from about "},{"text":"1 to 4kHz","b":true},{"text":" survives every playback system and carries speech intelligibility. If the mix works there, it works everywhere. If the mix depends on anything below 300Hz to sound full, it will sound thin to most of your audience."}]},{"t":"p","runs":[{"text":"This tells you where to spend care: consonant clarity, the relationship between dialogue and everything else in the midrange, and whether the music bed is competing in that band."}]},{"t":"h2","id":"checking-in-three-steps","runs":[{"text":"Checking, in three steps"}]},{"t":"p","runs":[{"text":"1. A phone speaker, at arm’s length, at low volume.","b":true},{"text":" Not earbuds: the built-in speaker. This is the most brutal and most representative test available, and it costs nothing. Listen for: can you follow the words, does the music vanish or dominate, is anything unpleasantly harsh."}]},{"t":"p","runs":[{"text":"2. Mono.","b":true},{"text":" Covered in the capture module for phase reasons, and it applies again here because most small speakers are single. One click."}]},{"t":"p","runs":[{"text":"3. Quietly.","b":true},{"text":" Equal-loudness contours mean the ear is far less sensitive to bass and treble at low levels than in the middle. A mix balanced at a comfortable monitoring level will sound midrange-heavy when quiet, and most listening is quiet. Mixing at moderate to low levels most of the time produces mixes that translate better, and it protects your hearing, which is the other reason to do it."}]},{"t":"h2","id":"reference-tracks","runs":[{"text":"Reference tracks"}]},{"t":"p","runs":[{"text":"The most reliable single technique: import two or three professionally finished pieces in the same genre, level-matched to your mix, and switch between them."}]},{"t":"p","runs":[{"text":"Level-matching is the step people skip and it invalidates the comparison if you skip it: louder sounds better, so an unmatched reference always wins or always loses for the wrong reason. Match by integrated LUFS using the meter from the loudness lesson, then compare."}]},{"t":"p","runs":[{"text":"Listen for the relationships rather than the tone: how loud is the voice against the music, how much low end is there, how bright are the consonants. You are checking your decisions against people who had better rooms and better monitoring."}]},{"t":"h2","id":"your-room-is-lying-to-you","runs":[{"text":"Your room is lying to you"}]},{"t":"p","runs":[{"text":"Every domestic room has strong low-frequency modes: peaks and nulls of 10dB or more at specific frequencies, determined by its dimensions. If your listening position sits in a null at 80Hz, you will add bass to compensate and your mix will be bass-heavy everywhere else. If it sits in a peak, the opposite."}]},{"t":"p","runs":[{"text":"Two cheap mitigations. "},{"text":"Headphones","b":true},{"text":" have no room, and while they misrepresent stereo width and bass extension in their own ways, they are consistent, and a known error is more useful than an unknown one. "},{"text":"Multiple systems","b":true},{"text":" average out individual errors: monitors, headphones, a laptop, a phone, the car. Anything that sounds right on four different systems is right."}]},{"t":"h2","id":"the-free-path","runs":[{"text":"The free path"}],"role":"free"},{"t":"p","runs":[{"text":"Everything here is free. A phone you already own, headphones you already own, "},{"text":"ffmpeg","b":true},{"text":" or any editor for level-matched references, and a mono button. "},{"text":"REW","b":true},{"text":" measures your room’s frequency response at the listening position for the cost of a measurement microphone, and even a rough measurement tells you where the big dips are."}]},{"t":"h2","id":"the-limitation","runs":[{"text":"The limitation"}],"role":"limit"},{"t":"p","runs":[{"text":"Translation checking tells you what is wrong and not what to do about it. A mix that sounds thin on a phone might need more midrange, less low end, a different arrangement, or nothing at all, because some material cannot survive a phone speaker and pretending otherwise ruins it everywhere else."}]},{"t":"p","runs":[{"text":"There is also no such thing as a mix that is optimal on every system. Decisions that help a phone (more midrange, controlled dynamics, less sub) cost something on a good system. Professional practice is to mix for the primary listening context and check that nothing breaks elsewhere, rather than to average across all of them and satisfy none."}]}],"check":{"question":[{"text":"A mix contains a deep sine-wave sub under a title sequence. It is clearly audible on monitors and completely absent on a phone, while a bass guitar in the same register comes through as a recognisable pitch. 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