Does the reverb sound like a real room or a hardware reverb unit?

No. It is a disclosed lightweight three-tap reflection design at 29.7, 37.1, and 41.1 milliseconds with weights of 0.50, 0.35, and 0.25 scaled by the chosen amount. It does not model a room, impulse response, diffusion, damping, or a professional reverb tail.

Is my audio uploaded when I process it?

No. File reading, decoding, sample processing, WAV encoding, and download creation all happen inside the current Safari tab. No audio is sent to a server and no account is required.

Why is the download a WAV and not an MP3?

The tool exports a fresh interleaved little-endian PCM16 RIFF/WAVE file. The source codec, bitrate, compression quality, tags, artwork, chapters, cue points, and loop markers are not preserved in the output.

Can I apply reverb and another effect in the same run?

No. The tool applies exactly one selected transformation per run. To combine effects, download the WAV and feed it back into the tool as the new input.

The reverb is too strong — what should I change?

Lower the amount slider in whole-number steps, since each tap weight is scaled linearly by the selected amount. If the output peak approaches the -1 through +1 floating range, dry and delayed samples overlapped and were clipped to the boundary; a smaller amount will reduce that overlap.

Add Reverb to Audio Online on iPhone Without an App

To add reverb to audio on an iPhone using only the browser, load the file into Audio Effects Online, pick the reverb effect, set a whole-number amount from 0 to 100, and download the resulting PCM16 WAV — the audio never leaves the device because every step of decoding, processing, encoding, and download creation happens inside the current Safari tab. This approach removes the need to install a dedicated iOS audio app or sign in to an account, which is useful when you want a quick space or depth treatment on a voice memo, a downloaded podcast clip, or a song demo recorded on the phone. iOS Safari supports the Web Audio API used to decode the file, so a wide range of common audio formats will decode in place, with some variation by browser version. Because the work runs locally, the original file stays untouched and can be re-run with a different amount or a different effect without losing the source. The reverb itself is a deliberately simple, disclosed three-tap reflection design rather than a modeled room or studio, so it suits quick sound-design drafts, podcast voice polish, or rough song sketches rather than final mixes.

Running Reverb Directly in the iPhone Browser

Browser-only audio tools answer a specific need on a phone: you do not want to grant another app microphone access, you do not want to commit storage to a niche audio editor, and you may not want to upload a recording to a remote server. A local tool sidesteps all three concerns at once. The browser tab opens, the file is decoded with the standard Web Audio API defined by the W3C, the chosen effect is applied to every sample frame in memory, and a new WAV is encoded and offered for download. Nothing is sent over the network.

For iPhone users this is convenient because the file picker in Safari reaches the Files app, Voice Memos, and iCloud Drive without extra setup. There is no companion app to keep updated, no in-app purchase to unlock reverb, and no account to register. The trade-off is scope: a browser reverb cannot replace a fully modeled convolution reverb in a desktop DAW, and you will not get multi-band EQ, sidechain processing, or stereo widening alongside it. What you do get is a predictable, repeatable space treatment that you can apply to one file in a single pass.

What the Lightweight Reverb Actually Does

The reverb shipped in Audio Effects Online is an early-reflection design, not a room or studio emulator. Three short delay taps are added to each dry sample at fixed positions, with disclosed weights that are scaled by the chosen amount. The tap timings, in milliseconds, are 29.7, 37.1, and 41.1, and the unweighted coefficients are 0.50, 0.35, and 0.25. Those numbers are deliberate product choices, not measurements of a concert hall, plate, spring, or any branded processor, and the result does not attempt to model frequency-dependent decay, stereo diffusion, damping, pre-delay, or a long reverb tail.

For a reader who wants the underlying math at one setting, here is the worked example at a 50% amount.

Step 1 — convert the amount to a multiplier: 50 ÷ 100 = 0.50.

Step 2 — multiply each base weight by the multiplier: 0.50 × 0.50 = 0.250; 0.35 × 0.50 = 0.175; 0.25 × 0.50 = 0.125.

Step 3 — add the effective weights to recover the wet energy at peak overlap: 0.250 + 0.175 + 0.125 = 0.550, meaning the three delayed copies together contribute 0.55× of the dry sample when all three taps land on the same dry frame.

Drop the amount to 25% and the same arithmetic produces effective weights of 0.125, 0.0875, and 0.0625, summed to 0.275 — about half the wet energy of the 50% case. Readers who want a deeper look at why these specific delay times were chosen can read the companion guide Reverb Delay Times Explained: 29.7, 37.1, and 41.1 ms.

Strong settings can clip because dry and delayed samples overlap, so the tool constrains every output sample to the legal -1 through +1 floating range before WAV quantization. The result is a quick space or repetition pass, useful for sound-design drafts but not a substitute for a true convolution reverb.

Apply Reverb to an Audio File on iPhone

Open Safari on your iPhone and visit Audio Effects Online.
Tap the file input and pick one audio file from the Files app, Voice Memos, or another source — keep it under 50 MiB and prefer a format your version of iOS Safari can decode (MP3, M4A/AAC, and WAV are broadly safe; FLAC support varies by iOS version).
Choose the reverb effect in the effect selector, then set a whole-number amount between 0 and 100. Start with a small value (around 20) to preview the space; raise it in steps of 10 to 20 until you reach the depth you want.
Tap Apply. Decoding and processing happen locally; the page reports channel count, sample rate, input frame count, output frame count, output peak, and the resulting WAV byte size.
Inspect the reported peak as a general headroom indicator. Because the output is constrained to the legal -1 through +1 floating range before WAV quantization, a peak approaching that range means dry and delayed samples overlapped and were clipped to the boundary; lowering the amount reduces that overlap.
Tap Download to save the new PCM16 WAV. On iOS Safari the download is offered through the standard download UI and lands in the Files app.
Keep the untouched original. Reverb with a different amount is a fresh run, not a chained edit, so the source remains your reference point.

iPhone and Safari File Considerations

Three practical constraints shape what you can realistically process on an iPhone.

Codec support is browser-dependent. The audio effects page accepts files by extension — MP3, WAV, M4A, AAC, Ogg, WebM, FLAC — but actual decoding is delegated to the browser's Web Audio implementation, per the W3C Web Audio specification. Files with recognized extensions are accepted, but a recognized filename does not guarantee that a particular encoded file will decode. If decoding fails, the tool creates no result.

WAV output is uncompressed. A 16-bit stereo WAV uses four bytes per frame (two channels × two bytes per sample), matching the PCM block alignment documented in Microsoft's WAVEFORMATEX structure. A four-minute stereo file at 44.1 kHz becomes roughly 4 × 60 × 44,100 × 4 ≈ 42 MB — large enough that free space on the phone is worth checking before you start.

One effect per run. The tool applies exactly one transformation and then encodes a fresh WAV. To compare reverb at 30% with reverb at 70%, run the file twice and compare the downloads. There is no multi-effect chain inside a single pass and there is no undo button, so the untouched original is your safety net.

Reverb and the Other Five Effects at a Glance

The reverb shares the page with five other operations. The table summarizes each one, what it does to the audio, and a typical reason to reach for it on an iPhone.

Effect	What it does	Typical iPhone use
Echo	Adds a half-strength copy of each input sample 200 ms later, scaled by amount.	Slap-back on a voice memo or spoken clip.
Reverb	Adds three reflections at 29.7, 37.1, and 41.1 ms with weights 0.50, 0.35, 0.25 scaled by amount.	Quick space or depth pass on a dry vocal or instrument sketch.
Reverse	Reads sample frames in opposite order and blends with the original by amount.	Pre-rolled effect, hidden transitions, creative stings.
Fade in	Scales from the dry proportion at the start to full level at the end.	Smooth opening for a voice memo or song demo.
Fade out	Scales from full level at the start to the dry proportion at the end.	Clean ending for a podcast clip or rough mix.
Normalization	Scales the largest absolute sample toward a 0.95 peak.	Raise a quiet recording before sharing; not a loudness match.

Limits Worth Knowing Before You Start

The reverb path has explicit ceilings, and the most important one is the output sample budget. The decoded input and the complete effect output may each contain no more than 30 million channel samples. Echo and reverb extend the file with a tail, so a long input that fits the input budget can fail the output budget and produce no file — in that situation nothing is truncated and nothing is downloaded. The reverb allocates its full tail up front, which is why the last reflection is not cut off.

Other boundaries are softer but still matter on a phone. The output is a single PCM16 WAV, which means the source codec, bitrate, tags, artwork, chapters, cue points, and loop markers are not carried into the download. Repeated lossy decode followed by PCM processing can reveal source artifacts, so it is wise to start from a clean recording rather than a heavily compressed clip when you want clean reverb. Normalization scales toward a fixed 0.95 peak and does not match perceived loudness across different recordings, so two files normalized separately will not necessarily sound equally loud side by side. Finally, all processing runs in the current Safari tab only — closing the tab before the download completes drops the result.