Acoustic uroflowmetry, also known as microphone-based uroflowmetry, is a newer method of measuring urinary flow. A phone or another microphone listens to the sound of urination. Special software then uses the audio recording to estimate parameters such as maximum urinary flow rate, average flow rate, voiding time and voided volume.
Because this method uses a microphone and artificial intelligence, many people ask:
Is acoustic uroflowmetry safe?
The short answer is: the use of a microphone to listen to the sound of urination is generally physically safe and non-invasive. The microphone does not touch the body, does not send electrical energy into the body and does not produce radiation as used in some other medical examinations.
However, it is important to distinguish between physical safety, data privacy and the medical reliability of the results.
What is conventional uroflowmetry?
In conventional uroflowmetry, the patient urinates into a special device – a uroflowmeter. The device measures the amount of urine, the flow rate and the duration of urination. The result is usually displayed as a urinary flow graph over time.
Most conventional uroflowmeters work by measuring time and the weight of the urine, from which all other parameters are calculated. This provides objectivity, repeatability and reliability.
Conventional uroflowmetry is used to assess problems such as a weak or interrupted urinary stream, an enlarged prostate, urethral narrowing, bladder dysfunction, overactive bladder and certain types of urinary incontinence.
Uroflowmetry is a non-invasive examination that is usually performed in a clinic. Patients have to arrive with a full bladder and urinate in an unfamiliar environment. Discomfort, time pressure or embarrassment may cause the result to differ from normal urination or home uroflowmetry.
How does acoustic uroflowmetry work?
In acoustic uroflowmetry, a phone or another microphone records the sound of the urine stream hitting the water or the surface of the toilet bowl. The software processes the audio signal and uses algorithms or artificial intelligence to estimate the urinary flow.
An application may calculate: maximum urinary flow rate, or Qmax; average flow rate, or Qavg; voiding time; estimated voided volume; a urinary flow graph; changes in results over several days or weeks.
Examples of this type of solution include applications that use a phone’s microphone to analyse the sound of urination without requiring a measuring container.
Is a microphone physically dangerous during urination?
No. In this application, the microphone only detects sound. If the phone is placed next to the toilet and does not come into contact with urine, the patient or water, the device does not enter the body and does not alter the act of urination.
In terms of how it is performed, acoustic uroflowmetry is therefore similar to other measurements in which a microphone listens to sounds from the surrounding environment. It does not involve a catheter, needle, ultrasound, X-rays or an electrical current passing through the body.
It is important, however, to protect the phone from contact with water and to use it according to the manufacturer’s instructions. The physical safety of the phone and microphone is not the same as the medical reliability of the measurement.
Does the application record my voice or everything happening in the bathroom?
This is primarily a question of privacy, not physical safety.
Acoustic uroflowmetry applications need access to the microphone in order to operate. During the measurement, they may therefore also detect other sounds in the environment, such as speech, a ventilation fan, toilet flushing or other background noise.
Before using an application, it is advisable to check:
- whether the audio recording is stored or processed directly on the phone or sent to the cloud;
- how long the data are stored;
- whether the entire audio recording is stored or only the calculated results;
- who has access to the data;
- whether the data can be deleted;
- whether the data is used to improve the algorithms.
Publicly available descriptions of some applications indicate that sound is used to calculate urinary flow. However, based solely on the public descriptions available at the time of writing, it is not possible to reliably confirm every detail regarding the storage of each audio recording. Users should therefore read the application’s privacy policy and terms of use before using it.
Is acoustic uroflowmetry accurate enough?
Research indicates that acoustic uroflowmetry can be useful and that its results maycorrespond well with conventional uroflowmetry. In one study involving adult men, very strong correlations were found between the acoustic and standard methods for maximum flow rate, average flow rate and voided volume. [ICS – validation study]
In a study involving children, acoustic uroflowmetry showed strong agreement with the conventional method for maximum flow rate, voiding time and voided volume. The correlation for average flow rate was not statistically significant. The authors therefore emphasised that further studies are needed in different toilet environments. [International Neurourology Journal]
More recent studies have also used machine learning to estimate urinary flow from audio signals. The results are promising, but accuracy depends on the quality of the recording, the position of the phone, the type of toilet, the amount of water in the bowl, the way the patient urinates and the level of background noise. [Scientific Reports – Flow prediction in sound-based uroflowmetry]
Acoustic uroflowmetry is therefore not necessarily equivalent to every conventional medical device under all conditions. The result should be understood as a measurement that may help monitor a patient’s condition, but it cannot by itself establish a diagnosis and may provide less information about the underlying condition of the lower urinary tract.
Comparison of conventional and acoustic uroflowmetry
| Feature | Conventional uroflowmetry | Acoustic uroflowmetry |
|---|---|---|
| Measurement method | A measuring sensor measures volume and time | A microphone detects the sound of urination |
| Setting | In a clinic and often at home | Often at home |
| Contact with the body | No direct contact with the body; non-invasive | No contact with the body |
| Comfort | The environment may feel less natural; home use is more natural | More similar to normal urination |
| Long-term monitoring | Occasional measurements may be sufficient | Multiple measurements over days or weeks |
| Effect of background noise | Usually limited | May be significant |
| Measurement traceability | Direct measurement | Algorithm-based estimation |
| Privacy | Device-generated data | Potentially also audio data |
| Clinical use | Established method | Developing method, dependent on the specific system |
Advantages of acoustic uroflowmetry
Many features are the same as with conventional home uroflowmetry: the possibility of measuring in the home environment, more natural urination, no need to travel to a clinic, no need to wait with a full bladder, and the possibility of repeated measurements.
A single uroflowmetry test may be influenced by the current level of bladder filling, the patient’s emotional state, privacy and other circumstances. Multiple measurements may provide a physician with a more realistic picture of the patient’s usual urinary pattern.
The main potential advantage of the acoustic method may be its cost, since it uses a phone or a small recording device. For the patient, it is simple to use and does not require cleaning a measuring container. Attention should nevertheless be paid to hidden costs, as subscriptions can significantly change the overall price.
Limitations and possible sources of error
Acoustic uroflowmetry is sensitive to the environment. Errors may occur if the phone is too far away, if the urine stream does not hit the water, if there is a lot of noise in the bathroom or if the toilet is flushed during the measurement.
For good accuracy and repeatability, the user should ensure that:
- there are no significant sources of background noise;
- the urine stream hits the same area of the toilet bowl each time;
- the phone is always placed in the same position and oriented in the same direction;
- the room remains, as far as possible, furnished in the same way, since sound reflections may affect the recording.
Different toilet bowls, different amounts of water, urinating while sitting or standing, and sudden interruptions in the audio signal may also cause problems.
For some systems, estimating voided volume can be particularly challenging. If the algorithm does not know the actual amount of urine, it must estimate the volume from the audio signal. This is not the same as directly weighing or measuring the urine.
Can acoustic uroflowmetry replace conventional uroflowmetry?
In some cases, acoustic uroflowmetry can significantly complement conventional measurements, particularly when monitoring patients at home and collecting a larger number of measurements.
However, it should not automatically be assumed that every application can replace a conventional medical uroflowmeter. Clinical use requires validation of the specific system, clear instructions, quality control, protection of health data and appropriate regulatory classification as a medical device.
All uroflowmeters intended for medical use fall under medical-device regulations and therefore require continuous oversight in accordance with the applicable regulatory requirements. It is advisable not to use applications or devices that have not undergone the appropriate certification or regulatory assessment.
If a patient has significant urinary problems, pain, blood in the urine, an inability to urinate or recurrent urinary tract infections, the use of an acoustic application should not delay an examination by a physician or urologist.
Final answer: Is acoustic uroflowmetry safe?
From the perspective of its physical effect on the body, acoustic uroflowmetry is generally very safe because it is a non-invasive method that listens to the sound of urination. The main concerns are not injury or radiation, but data privacy and the reliability of the algorithm.
Acoustic uroflowmetry can be very useful for home monitoring, especially when it enables multiple measurements in the patient’s normal environment. Conventional uroflowmetry, however, has the advantage of direct measurement and established clinical use.
The most sensible solution is therefore not necessarily to choose only one method. For many patients, home acoustic measurements may complement conventional uroflowmetry and give the physician a broader insight into the patient’s everyday lower urinary tract function.
If you are considering measuring urinary flow at home, choose a system that clearly explains its measurement method, limitations, data protection and intended use. Always interpret the results together with your symptoms and, when necessary, with the professional opinion of a urologist.
Frequently asked questions
Does acoustic uroflowmetry hurt?
No. The microphone only listens to the sound of urination, so the method does not cause pain and does not require an invasive procedure.
Do I need a special toilet?
It depends on the application. Some solutions use an ordinary toilet, but the phone must be placed correctly so that it can detect the sound of the urine stream with sufficient quality.
There should be no significant background noise. The urine stream should hit the same area of the toilet bowl each time, the phone should always be placed in the same position and oriented in the same direction, and the room should ideally remain furnished in the same way because sound reflections can affect the measurement.
Is acoustic uroflowmetry suitable for men and women?
Potentially, yes. However, the specific application must be validated for the intended users, urination positions and environments in which it will be used.
Can an application detect an enlarged prostate?
Not directly. A weaker urinary stream may be associated with an enlarged prostate, urethral narrowing, reduced bladder function or other causes. Only a physician can make a diagnosis based on the complete clinical picture.
Which is more accurate: a conventional uroflowmeter or a microphone?
A conventional uroflowmeter measures flow or weight directly. The acoustic method estimates flow from sound, so its accuracy depends on the algorithm and the recording conditions. The comparison always depends on the specific device or application.
All uroflowmeters intended for medical use fall under medical-device regulations and therefore require continuous oversight in accordance with the applicable regulatory requirements. It is advisable not to use applications or devices that have not undergone the appropriate certification or regulatory assessment.