Ear Impressions for Custom IEMs: A UK Guide for Musicians and Crew

Last updated 11 November 2026. First published 10 September 2024.

The short answer: custom in-ear monitors (IEMs) are made from silicone impressions of your ears, taken by a trained clinician, or from a 3D scan. For Ultimate Ears (UE), the impression has to include the whole outer ear and run just past the second bend of the ear canal, or UE rejects it. Allow about half an hour for the appointment, ask the clinic for a price first, and expect UE’s build to take about 10 business days once it has usable impressions.

If you are ordering through TourStock, our designer lets you upload an .stl scan, tell us where your impressions already are, or ask us to book an appointment anywhere in the UK for a flat £150 plus VAT (£180 including VAT).

In this guide

• What ear impressions are
• What a usable impression looks like
• Where to get ear impressions in London and the UK
• How to prepare
• What happens at the appointment
• Cost and timing
• Common mistakes
• How impressions fit into UE’s build, and ours
• FAQs and sources

What ear impressions are

An ear impression is a silicone cast of your ear: the folds of the outer ear and the canal leading in towards the eardrum. A custom IEM maker uses it as the blueprint for a shell that fits only you. UE notes that, like a fingerprint, each of your ears is distinct in shape, depth and size.

The fit decides the seal, and the seal decides how well the monitor isolates. UE quotes up to −26 dB of isolation for its custom IEMs, and says that figure “assumes a proper ear impression, excellent fit and seal and use of both IEMs”. A poor impression can cost you the isolation you bought custom IEMs for.

A note on words: in UK audiology the cast is the impression, and the earpiece made from it is the earmould. UE’s own pages also say “molds” for impressions, so you will see both. Impressions are used for other custom ear products too, such as earplugs, but for IEMs the requirements are different, as the next section shows.

What a usable impression looks like

UE publishes a one-page set of requirements for the clinicians who take impressions for its in-ear monitors. In short:

• The whole outer ear, not just the canal. UE’s professional IEMs need a full-shell earpiece, so the impression must include the full helix, the crus of the helix, the tragus and the antitragus.
• Deep enough. It must be taken just past the second bend of the ear canal.
• The right materials. High-viscosity silicone, with cotton or foam canal dams, the small blocks placed in the canal so the silicone cannot travel past them.
• Stillness. No talking or jaw movement while the silicone cures.
• For singers, a bite block. UE does not require one, but recommends a ½ inch bite block for singers, to capture how the canal narrows with the mouth open.
• An IEM-grade seal. UE says moulds for in-ear monitors are different from hearing-aid and earplug moulds, and that custom IEMs for musicians must have a full seal.

UE adds that impressions without every key point are rejected, and that a bad impression means a second trip to the clinic.

Print UE’s one-page audiologist requirements and take them with you.

Where to get ear impressions in London and the UK

The route is the same in London as anywhere else in the UK, and so is the standard: UE’s requirements above. Here are two routes.

1. Through TourStock

In our Ultimate Ears custom IEM designer you choose how your impressions will reach UE: upload an .stl scan, tell us where your impressions already are, or ask us to book an appointment anywhere in the UK. Nothing is ordered or charged until you approve the quote.

2. A private audiology clinic or hearing-care practice

UE’s advice is to search for “audiologists near me” and pick a professional who specialises in ear impressions for in-ear monitors for musicians, and to take its audiologist instructions along. Tell the clinic up front that the impressions are for UE custom IEMs, not hearing aids or earplugs.

In the UK, “audiologist” is a broad, widely used description, while “hearing aid dispenser” is a legally protected title for clinicians registered with the Health and Care Professions Council (HCPC). Ask what registration the clinician holds; you can check a registration on the HCPC register. Some clinics send your impressions to the maker for you, others hand them back to you, and some offer mobile or studio visits.

Questions to ask before you book

General advice, not from a source: these are the questions we would ask.

• Have you taken impressions for custom IEMs before, and can you follow UE’s requirements: the whole outer ear, just past the second bend?
• Can you use a bite block if I sing?
• How long should I book?
• What does it cost, and does that include wax removal if I need it, or a retake if UE rejects the impressions?
• Will you post the impressions on, or do I?

How to prepare

1. Start your order first. UE sends its audiologist instructions after you order, and clinics advise settling on the maker before the appointment. In our designer, choose your impressions route and we arrange the rest with your quote.
2. Take UE’s one-page requirements with you. The link is above.
3. Deal with earwax beforehand. Wax can stop the appointment going ahead, so sort it out first.
   • The British Society of Audiology (BSA) says excess wax should be removed before impressions are taken, or it can be pushed further in or distort the shape of the cast.
   • Some clinics quote wax removal separately.
4. Tell the clinician about anything unusual. Mention any ear surgery, pain, infection or tinnitus. BSA says it is safer not to take an impression with an active outer-ear infection or discharge from the middle ear, and that impressions should be avoided straight after ear surgery until the ear has healed.
5. If you sing, raise the bite block. UE recommends one for singers.
6. Work back from your deadline. Your total timeline depends on how quickly you can book the appointment and get the impressions to UE, on top of the build time. If you have a needed-by date, add it in the designer, which shows which turnaround fits.

What happens at the appointment

BSA publishes a recommended procedure for taking an aural impression. UE describes the IEM version in its own words. In outline:

1. Questions and an ear check. The clinician asks about ear surgery, pain or infection and looks in your ear with an otoscope.
2. A canal block goes in. A small foam or cotton block (an otoblock or otostop) is placed in the canal, to just beyond the second bend, about halfway along it, and checked for gaps. It acts as a seal.
3. The silicone goes in. It is syringed in and fills the canal and the outer ear. UE describes it as cool and gooey, much like a dental impression.
4. You sit still and stay quiet while it sets. UE says it takes “several minutes”. If a bite block is used, your jaw stays open on it.
5. What you will feel. Fullness in the ear, possibly a cough reflex as the block goes in, and a temporary rise in tinnitus if you have it. You can raise a hand if you need to stop.
6. Removal. The clinician checks the silicone has set, then eases the impression out, breaking the air-tight seal first. UE says impressions are “carefully spun out”, which can be temporarily uncomfortable. Moving your jaw gently from side to side can help.
7. The check. The clinician should check the impression is complete, repeat it if it is not, and look in your ear again to make sure nothing is left behind.

After that, the impressions go to the maker. BSA’s guidance for earmoulds says impressions should not be trimmed before dispatch, because the lab uses their full length. UE says it scans every physical impression, keeps the originals on file and does not send them back.

Cost and timing

Cost

• Clinics set their own prices. General advice: ask for a quote before you book, and check whether wax removal, a retake or a scan is extra.
• Through TourStock, we can book an impression appointment anywhere in the UK for a flat £150 plus VAT (£180 including VAT). The designer shows each price excluding VAT first, with the VAT-inclusive figure beneath, and we confirm your price in the quote before anything is ordered.
• If you already have impressions or an .stl scan, you can send them with your design.

Timing

1. The appointment. Clinics that take impressions for musicians typically allow around 30 minutes. General advice: an IEM impression is deeper and takes more care, so ask the clinic how long to book.
2. Getting the impressions to UE. Do not overlook this step. UE’s own pages say your timeline also depends on how quickly you book the appointment and get the impressions delivered.
3. The build. UE’s pages give about 10 business days from the day it receives your impressions. Our designer says standard production is usually about 14 calendar days, and that timings depend on UE and your impressions being usable.
4. Delivery. This comes after production, so allow for it.

Rush production is available if you have a hard date; the designer shows the options for your needed-by date.

Common mistakes

• Treating it like a hearing-aid mould. UE says IEM impressions differ from hearing-aid and earplug ones, so tell the clinic what they are for.
• Stopping short. Impressions that do not reach just past the second bend, or miss part of the outer ear, are rejected.
• Talking or moving your jaw while it sets. UE and BSA both ask you to stay still and not talk.
• Skipping the wax check. Wax can stop the appointment going ahead or distort the cast.
• Forgetting the bite block if you sing. UE recommends one for singers.
• Trimming or tidying the impressions. BSA says not to trim them before they go to the maker.
• Doing it yourself. UE’s custom IEM pages call for impressions taken by a licensed audiologist, or a digital scan, and BSA warns that a canal block pushed deeper than needed can cause discomfort and possible injury.
• Leaving it late. The appointment, getting the impressions to UE and the build all sit in front of your deadline.
• Reusing old impressions without asking. UE says ears change shape over time and holds impressions on file for up to five years.

How impressions fit into UE’s build, and ours

UE describes its process like this: it begins with an ear impression taken by an audiologist and sent to UE for review. The impressions are then scanned and 3D printed to make a shell that matches your earprint. Technicians assemble the wiring, sound tubes and filters by hand, test each monitor, then buff, polish and customise it before a final quality check.

Through TourStock, the steps look like this:

1. Design. Pick a model, then choose faceplates, halo, logo and cable for each set.
2. Impressions route. Upload an .stl scan, tell us where your impressions are, or ask us to book an appointment.
3. Quote. We check every detail and send a quote. You can change anything before you approve it, and nothing is ordered or charged until you do.
4. Impressions reach UE. If you have physical impressions elsewhere, tell us where they are and we will advise. UE’s own instructions are written for its US store and tell customers to post impressions to California, so general advice: do not post anything until we have told you where to send it.
5. Build. UE builds and tunes your set from your impressions.

When the set arrives, we also sell IEM cables, cleaning kit and hearing protection: browse IEM cleaning and maintenance, IEM cables and IEMs and hearing care. We deliver, or you can collect from our London shop at Ground Floor, 60 Weir Road, London SW19 8UG. Choosing a model first? The designer shows all eight UE custom models side by side.

Sources

All checked on 11 November 2026. UE’s pages are written for its US store, so where they differ from our designer, for example on where impressions are sent, follow the designer.

• Ultimate Ears Pro: Ear impression requirements for audiologist partners (one-page PDF)
• Ultimate Ears Pro Support: UE Pro audiologist impression
• Ultimate Ears Pro Support: What is it like to get audiologist impressions?
• Ultimate Ears Pro Support: Custom IEM support and FAQs
• Ultimate Ears Pro Support: UE Pro Learn FAQs
• Ultimate Ears Pro Support: What makes Ultimate Ears Pro so special
• Ultimate Ears Pro: Custom IEMs and UE 5 Pro
• Ultimate Ears Pro: Custom vs. universal IEMs for singers
• British Society of Audiology: Recommended procedure: taking an aural impression (OD104-33, PDF)
• Health and Care Professions Council: How to check and find a health and care professional
• British Society of Hearing Aid Audiologists: Become an audiologist
• TourStock: Ultimate Ears custom IEM designer