Echotect: Turn your hood into a delay

Echotect turns real-world map geometry into musical delay structures. Place a Source and Listener, then add Reflectors directly or derive them from nearby surfaces with the Echo field. Audition the result in the browser, save it as an editable project, or export it as audio and portable project data.

See it live: https://janne-s.github.io/Echotect/

How it works

All Reflectors participate in the same path model, including reflections between surfaces. Longer paths arrive later and lose more level and high-frequency energy; materials shape their absorption, and the spatial mode controls how the result is heard. Audio can be exported as impulse responses, a wet render, or aligned stems.

Map, Image, and Terrain are independent layers, and only the active one is heard. Map and Image share the Source, Listener, reflectors, and structures; Terrain has its own Source and Listener.

Use Save and Open for editable project files. Use Export for audio and project manifests.

Reset app in Settings clears Echotect’s saved workspace, view, settings and session search cache, then reloads after confirmation. Boomtect’s data and downloaded files are kept. Reset is available even if the main application fails to start. Recover audio restarts only the audio engine. Interrupted audition stops; Play starts it again. Audio preparation can be cancelled, and startup failures appear beside the playback controls.

Structures are editable polygons in Map and Image modes. Their edges provide reflective surfaces to the Echo field.

Boomtect

A sound from Boomtect arrives with its place: Send to Echotect in Boomtect's export opens Echotect with it, or choose Boomtect's Echotect package (ZIP) as your own sound. As Boomtect's Echotect with chooses: with Place, the Listener goes where the microphone was and the Source the way the sound came from, at its distance and height; with Direction, only the Source moves; with Sound only, nothing does, and the sound simply replaces the current one. The sound already holds the air along that distance, so only the rest of each path is absorbed. Reflectors stay where they are. A sound longer than two seconds plays Rendered, since Live cannot start that many long voices in time.

Heights

In Map and Image, Source height and Listener height set how high each stands above the ground. Every reflector is a vertical wall, so a path from a high Source reaches the Listener at an angle, and it passes over a wall where it meets the wall above the building's height. Building heights come from the map data when it has them; a wall of unknown height is never passed over. The late field stays level.

Buildings

• Buildings — Shows building footprints on the map.

Image

• Image — Places a PNG, JPEG, or WebP image over the map. The image is saved in the project.
• Scale — Sets the image scale from a known distance between two points.
• Rotation — Rotates the image.
• Opacity — Sets how much of the map shows through the image.

Terrain

• Terrain — Uses the elevation data inside a drawn rectangle as the echo field, or switches between the map and the saved terrain. The rectangle can be moved and reshaped.
• + — Draws a new terrain in place of the saved one.
• Relief — The mountain button beside the zoom controls switches the map to shaded relief.
• Space panel — Shows the terrain in 3D or as a section through the Source and Listener, in the side panel or its own window.
• Canyon / Chamber — Canyon reflects from the terrain surface. Chamber uses the terrain as a hollow above a flat floor. Each keeps its own Source and Listener placement.
• Floor — Sets the Chamber floor height.
• Scale — Scales the acoustic space from 1:100 to 10:1. The map does not change.
• Listener height / Source height — Sets the height above the ground, or above the Chamber floor.
• Material — Sets the absorption of the terrain surface.
• Scattering — Balances discrete echoes and diffuse scattering.
• Ground reflection — Sets the level of the reflection from the ground under the Source and Listener.
• Delete terrain — Removes the saved terrain.

Echo field settings

• Playback mode — Plays directly in Live mode or prepares a reusable browser render when Rendered is selected. Cancel stops waiting for a render, which stays usable until the sound, the geometry, or a setting changes.
• Defaults — Sets the Echo field settings back to their defaults; Save settings keeps them.
• Block reflections through buildings — Prevents Echo field surfaces from reflecting sound to each other through intervening buildings.
• Point reflections — Chooses between a longer, more diffuse point-reflection response and stricter geometric decay.
• Point persistence — Sets how strongly sound continues between Point Reflectors in Persistent mode.
• Point bounces — Limits how many times a point-reflection path can bounce.
• Point path limit — Limits the number of point-reflection paths used.
• Atmosphere — Uses standard air conditions, custom conditions, or disables atmospheric timing and absorption adjustments.
• Temperature — Sets the air temperature for Custom atmosphere mode and changes the speed of sound used for every propagation time.
• Relative humidity — Sets the humidity for Custom atmosphere mode, including its smaller contribution to the speed of sound.
• Air pressure — Sets the air pressure for Custom atmosphere mode.
• Air attenuation scale — Adjusts the strength of air absorption; 1.00× ISO is the normal model and 0.00× disables its effect.
• Geometric spreading — Controls level loss over distance; 1/r is the natural setting and Off removes this loss.
• Material absorption scale — Adjusts how strongly reflector materials color and absorb the sound; 1.00× uses the normal material presets.
• Late field — Selects the Sampled paths response or the Feedback network.
• Late field level — Adjusts the level of the late response in decibels.
• Response duration — Sets the maximum Sampled paths response length.
• Echo field surfaces — Limits how many nearby building or terrain surfaces are used.
• Late path samples — Sets how many sampled paths form the late response.
• Late field bounces — Limits the number of surface bounces in the late field.

Max for Live

Echotect Field is one consumer of Echotect's JSON project manifest. It brings the geometry into Ableton Live to recreate its direct sound and reflection delays, with real-time controls for timing, direction, width, path count, and the balance between the input and reflected sound.

The Max for Live device is functional, but still rudimentary and under development.

Data attribution

Map and building layers retain their required attribution in the application. OpenStreetMap data is © OpenStreetMap contributors. Overture Maps building data is licensed under ODbL. The optional relief map uses OpenStreetMap data and SRTM/Sonny elevation with the OpenTopoMap style under CC BY-SA. Terrain capture elevation comes from Terrain Tiles on AWS Open Data, compiled by Mapzen from SRTM, GMTED2010, NED, ETOPO1, and national datasets; see their attribution list.

Support Echotect

Support development through GitHub Sponsors or Ko-fi. See Sanara Creations for related work.