Acoustic water leak detector on your phone: listening, calibration and a survey map
You are standing on a tiled villa floor and the customer asks, “So where exactly is the leak?” Your listening device gives you sound in your ears and nothing else, and judging which point is louder depends on your memory of what you heard and on how quiet the house is.
This guide explains the Acoustic Leak Listener in Kashf Pro: an acoustic water leak detector that runs on your phone, using its own microphone or an external sensor. It turns what you hear into numbers you can compare: a leak score, energy above the noise floor, the type of sound (hiss or tone), a survey map that marks the loudest point, and a report you can share with the customer.
What is a phone-based acoustic water leak detector and what does it give you?
It is a tool inside the Kashf Pro app. It takes sound from an input you choose, filters it to the frequency band where leak noise lives, and analyses the spectrum on your phone ten times per second.
It gives you four things:
- A leak score from 0 to 100, shown in green, amber or red, with an alert and a vibration when the hiss persists.
- A live spectrogram showing time, frequency and intensity.
- A survey map on a grid of squares, with a “reading gets stronger this way” arrow and a star on the loudest point.
- A report with a link you can share with the customer, including the map and the spectrogram.
Who is this tool for?
For leak detection technicians who work by listening, whether independent or employed, including technicians from other companies. It also helps engineers and property managers document listening points with numbers.
It does not teach listening from scratch. It assumes you know how the pipework is routed and how to isolate and pressurise the network.
When do you use it?
- After a meter test or a pressure test has proved there is a leak on a pressurised line and you want to narrow down its location.
- When you want to compare many points on a floor or wall in a documented way instead of relying on memory.
- To confirm a point before opening up, or to convince the customer with the spectrogram and the map.
Do not start with it before the leak has been proved, and do not use it on unpressurised drain lines. Leak hiss needs water under pressure.
Where do you use it?
On floors and walls above the hot and cold supply pipes, on exposed valves, stop taps and meters, and in bathrooms, kitchens and corridors.
Many Saudi homes are fed from a tank and a booster pump, so the line after the pump is only pressurised while the pump runs, or carries gravity pressure from a roof tank. Make sure the suspect line is under pressure while you listen.
What do you need before you start?
- A Kashf Pro account with a subscription, a trial or credits. Each listening session counts against your plan's limit.
- A modern browser on Android or iPhone, with microphone access allowed. The tool also asks for device orientation (compass) access where available.
- An audio input: the phone microphone is enough to start. Results are better with a contact microphone or ground sensor through the AUX port (with a TRRS adapter) or a USB-C audio adapter, or with the headphone output of your own detection unit.
- Wired headphones if you want to hear the filtered sound.
- A rough plan of the pipe routing, and air conditioners, pumps and washing machines switched off where possible.
How to use it correctly, step by step
Acoustic Leak ListenerSubscription — free trial available
The tool opens the input you choose, in two channels where possible and at 48 kHz if the device supports it, and asks the browser to turn off echo cancellation, noise suppression and automatic gain control. Those processes hide faint hiss.
The sound then goes through a digital gain of ×1 to ×30 and a 4096-point spectrum analyser. Every 100 milliseconds the tool calculates three features inside the pipe band you selected:
- Above noise (dB): the average energy in the band compared with the calibrated noise floor.
- Spectral flatness: from 0 to 1. Broadband hiss is close to 1 and a pure tone is close to 0. It is calculated only on bins that rise above the noise.
- Tonality (dB): how far the highest peak stands out from its neighbours. Pumps and air conditioners produce sharp peaks.
The tool also measures how stable the energy has been over the last two seconds. It combines all of this into the leak score = 4 × above noise + 60 × flatness + 20 × stability − tonality, clamped between 0 and 100. If the energy is less than 3 dB above the noise, the score stays low.
There are three preset bands: plastic pipes (PPR/PVC/PE) from 100 to 900 Hz, metal pipes from 400 to 3000 Hz, and a wide band from 150 to 2500 Hz. The platform administrator may adjust them.
Steps for correct use
- Choose the input and the band
Open the tool from the app's home screen. From the Audio input list choose the phone microphone or the connected external device. Input names appear after you first allow microphone access. Then choose a Pipe type / band: plastic for most modern home plumbing, metal for steel and copper, and wide if you do not know the material.
- Set the gain, then start
Set the digital gain before calibrating. Start at ×1 with a strong external sensor and raise it to ×5 or ×10 with the phone microphone. Then tap ▶ Start listening; a session is counted only after you allow the microphone. If you change the gain after calibrating, the tool scales the calibrated noise level by the same ratio and warns you, so do not change it during a grid survey if you want a fair comparison.
- Calibrate the noise at a quiet point
Place the sensor on the same kind of surface (tile on tile) at a point far from the suspected area, tap Calibrate noise (3 s) and keep quiet. Without calibration the tool shows “⚠️ Calibrate the noise first” and uses an automatic estimate that falls slowly and never rises, so a constant hiss is not absorbed over time. But if that estimate starts over the leak, it treats the hiss as noise from the beginning and the score drops; only manual calibration raises the reference noise level.
- Set up the survey grid
In the Acoustic survey map choose 2 to 6 rows and 2 to 8 columns, and divide the floor or wall into equal squares, mentally or with masking tape. Example: a corridor 4 m long and 1.5 m wide suits 3 rows × 8 columns, roughly 50 cm apart.
- Record every square the same way
Tap the square you are standing on to select it and place the phone or sensor on it with the same pressure and position each time. Wait two seconds for the number to settle, then tap 🎙 Record this square (3 seconds). The tool stores the average “above noise” value and the compass heading, and after two points the arrow and the star appear.
- Check, then save the report
At the loudest point tap 🧠 Check with AI. Only the spectrogram (as an image) and the calculated features are sent, never the audio. Then tap 💾 Save result and create report to get a link containing the heat map and the spectrogram.
How to read the result
The ring and the score: green below 35 means no leak signature here. Amber from 35 up to the alert threshold means a faint continuous sound, so keep surveying. Red is at or above the alert threshold, 60 by default and adjustable by the platform administrator. If the score stays red for about a second and a half, the frame flashes, the phone vibrates and the message “Continuous hiss signature — move slowly and compare with neighbouring points” appears.
The four readouts:
- Above noise (dB): the higher it is, the louder the sound compared with the background.
- Hiss / tonal with the flatness value: “Hiss” means flatness above 0.2 and tonality below 15 dB. When it is quiet (less than 3 dB above noise) “Quiet —” is shown instead of a label.
- Peak frequency in hertz.
- Phone heading in degrees from the compass.
If the input has two channels that are genuinely different, a left/right bar compares their energy. If the two channels are almost identical (the phone duplicating one microphone), the bar stays hidden.
The map: the loudest square carries a ★. The arrow points to the neighbouring square that is louder than your current one, and 🎯 means you are at the loudest point. If you see “No louder neighbour — compare with the ★ square”, you may have two peaks, so record more squares around both.
The classification after the check is calculated on the server with fixed formulas:
- “No distinct sound above the noise”.
- “Tonal sound (pump / air conditioner / motor)”.
- “Intermittent / passing sound”: repeat when it is quiet.
- “Continuous hiss signature — leak likely near this point”.
- “Faint continuous sound — compare with neighbouring points”.
The AI opinion only appears when an AI provider is connected to the platform. If it is not, the tool says the AI review is unavailable and the deterministic classification remains.
Why can you hear a leak, and how do you choose the band?
When pressurised water escapes through a crack or a joint, the turbulence creates a broadband sound that resembles a hiss. That sound travels along the pipe wall and through the water, then through soil and concrete to the surface.
- Plastic pipes (PPR, PVC and PE) absorb high frequencies quickly, so the sound arrives low, weak and only over short distances. That is why the plastic band in the tool runs from 100 to 900 Hz.
- Metal pipes carry sound further and at higher frequencies, so their band runs from 400 to 3000 Hz.
- Pressure makes the hiss louder, and a line without pressure makes almost no sound.
The difference between a leak and background noise is exactly what the tool measures. Leak hiss is continuous, stable and spectrally flat. Pumps, air conditioners and transformers produce sharp horizontal lines on the spectrogram, while footsteps and doors produce intermittent blotches. That is why tonality is subtracted from the score and stability is added to it.
A single microphone cannot tell direction on its own. Direction comes from comparing points on a regular grid, which is what the survey map does.
Connecting external equipment in practice
The phone microphone
The bottom microphone is usually the main one. Lay the phone face down or face up so the microphone touches the tile, and cover it with a cloth or foam to block air noise. Do not hold it while recording, because finger friction shows up as broadband noise that looks like hiss.
Contact or ground sensor
Through the AUX port, use a TRRS adapter made for microphone input, because an ordinary headphone adapter does not carry the microphone signal. Through USB-C, use an audio adapter that supports a microphone or a small audio interface. After connecting, reopen the Audio input list and choose the device by name.
Your detector's output
If you have an electronic listening unit with a headphone output, connect that output to the line or microphone input of a USB adapter. Turn the unit's volume down and start at ×1 gain so the signal does not clip. This way you keep your unit's sensor and filters and add documentation and the map on top.
Some phone operating systems keep part of their audio processing however the tool asks to switch it off. If you notice the noise being “squashed” automatically, try an external input.
Common mistakes that spoil the result
- Calibrating over the leak: this turns the hiss into the “noise floor”, so every score around it drops. Calibrate far away and on the same type of surface.
- Changing the gain mid-survey: the tool scales the calibrated noise by the same ratio, but squares recorded before and after the change are not fully comparable. If you change it, recalibrate and start the grid again.
- Different positions between squares: a different pressure on the sensor, tile versus carpet, or the phone with a cloth one time and without it the next changes the reading more than the leak itself.
- Recording before it settles: stability is calculated over the last two seconds, so wait that long after placing the sensor.
- Leaving the pump and air conditioning on: the tool usually labels them as tonal, but they raise the noise and mask faint hiss.
- Listening to an unpressurised line: if the pump is off and the roof tank is empty, you will hear nothing.
- Listening through the phone speaker: it causes feedback and whistling. Use headphones.
The honest limits of the tool
- It is an aid for analysing sound, not a calibrated detection instrument. Accuracy depends on the quality of the microphone or sensor, how quiet the site is, the type of floor and the depth of the pipe.
- A single microphone cannot tell direction. The arrow comes from comparing squares, and the compass only records which way the phone faces, not where the leak is. The left/right bar is useful with two real sensors and does not appear if the phone duplicates one microphone on both channels.
- It does not work on unpressurised drain lines, and it does not hear well through thick insulation layers or deep, loose soil.
- The AI opinion needs a connected provider and has a call limit per session. It only reads the spectrogram image.
- Audio is analysed on your phone and is not uploaded. Only what you choose to analyse or save is uploaded.
- The result supports your judgement and does not replace it. Confirm with a second method before opening up, such as thermal imaging, tracer gas or isolating lines under pressure.
When to escalate or ask for a second opinion
- Two or more peaks on the map, the loudest point under a kitchen or between two rooms, or an amber score everywhere. Tracer gas or a pressure test on each line separately helps here.
- Deep plastic lines or double-layer tiling where the sound becomes very weak.
- The customer needs a documented technical report from a detection company to give to the water utility or an insurer.
- Cracks in concrete slabs or columns, or a sinking floor. These need a licensed structural engineer before anything is opened up.
- Water near electrical installations: switch off the power first; safety comes before detection.
In these cases you can ask the Kashf team, which works in Saudi Arabia, for a second opinion or subcontract them. The team detects leaks electronically without breaking, using acoustic and thermal equipment, pressure testing and tracer gas, and hands over a written report that can be checked on the verification page. Book from the order page or on WhatsApp at +966544027180.
Frequently asked questions
Is the phone microphone good enough as an acoustic water leak detector?
It is enough to start in quiet places and with strong leaks close to the surface, especially when the microphone touches the tile and you cover it with a cloth. For faint leaks or deep plastic pipes you will get better results with a contact or ground sensor connected through AUX or USB-C, or with the headphone output of your own detection unit.
Can the tool tell the direction of the leak from where I stand?
No. A single microphone does not know where a sound comes from. Direction emerges from comparing squares on the map, where the arrow points to the neighbouring square with the higher reading. The compass records which way the phone faces only to document your position. To locate a point on a pipe between two access points you need the correlator with two separate sensors.
Why does the score drop over time while I stay on the same point?
Usually because you did not tap the calibrate button. The automatic noise estimate never rises, but it starts from the first thing it hears, so if you start listening over the hiss it treats it as noise from the beginning. Tap “Calibrate noise” at a quiet point far away before surveying, and the readings will hold steady.
What is the difference between the plastic, metal and wide bands?
Plastic absorbs high frequencies, so its leak noise stays roughly between 100 and 900 Hz. Metal carries higher frequencies, from 400 up to 3000 Hz. The wide band covers 150 to 2500 Hz for mixed or unknown cases. Choosing the right band excludes noise outside it and widens the gap between the leak and the background.
How many times can I use the tool on my plan?
Each plan has a monthly limit per tool, and some plans make it unlimited. Usage is counted per session, and a session stays valid for a set time from when it starts, so restarting within it costs nothing extra. When the limit runs out you can upgrade or buy usage credits on the website.
Is the customer's audio or a recording of the site uploaded to the internet?
No. Sound analysis happens on your phone. When you tap the AI check, only the spectrogram image and the calculated numbers are sent, and when you save, the map and spectrogram images are uploaded to the report. The tool is meant for pipe and water sounds, as set out in the terms of use.
How do I know the sound is a pump and not a leak?
Pumps and air conditioners show up on the spectrogram as sharp horizontal lines, so tonality rises, flatness falls and the tool shows “tonal” instead of “hiss”. Try switching the pump off once the line is full and pressurised; if the steady hiss remains, it is a leak candidate.
Can I rely on a red score and open the floor straight away?
No. A red score means a continuous hiss signature near that point, but it does not replace confirmation. Compare neighbouring squares, check the pipe route and confirm with a second method such as thermal imaging, tracer gas or isolating the line under pressure before opening anything. The final decision is yours.
What does the report I share with the customer contain?
It contains the survey heat map with the loudest point, the spectrogram, the band used, whether calibration was done, the last reading and the classification if you requested it. It opens from a link and you can delete it from “My saved results”. A short line introducing Kashf Pro may appear at the bottom.
This guide is educational. It explains estimation tools that help you understand a situation and decide what to do next; confirming a leak and pinpointing it always requires an on-site inspection with instruments. Structural questions are for a licensed engineer to decide.