Identifying Defect Detectors

CSX Talker

CSX has developed an in-house talker unit in lieu of utilizing commercially available products like the Progress Rail Micro Talker or the STC iCUBE. These units can be found on Wheel Impact (WILD) detectors and high/wide clearance detectors throughout the CSX system.

The female voice heard on these units is the same as used on their radio-controlled remote switches & radio-activated crossings/warning devices.

CSX Talker - WILD

Of all of the detector manufacturers, Devtronics models are among the hardest to pin down, particularly on CSX where the first talking detectors extended back to the Atlantic Coast Line days. The 68178, 68278, and CMA02 models all utilized a 9 track tape that used audio tones for timing of words. As the tapes were recorded as the units were replaced, a variety of different voices emerged, and it can be difficult to discern a model solely from the voice.

The S.C.A.T. (Supervisory Control Alarm Telemetry) unit was not capable of detecting hot bearings, and was thus utilized primarily as a dragging equipment or high car detector.

CMA02 - Milepost
CMA02 - Location Name
Either a 68178 or 68278
Harmon Industries

Harmon has been around for a long time, with many talking defect detector models. However, most of these units share the same two voices, making them all but impossible to differentiate without seeing what's inside the bungalow. Models sharing the same two voices include the Mini Talker II, the Model 34, the Model 46, and the Model 75, among others.

One notable variation were Southern Pacific's custom female voices.

The only Harmon unit with a voice unique to itself is the Cyberscan 2000, introduced in the mid 1990s. A notable variation were the CN units which utilized a custom Canadian male voice.

Harmon - Standard Voice
Harmon - Alternate Voice
Harmon - Southern Pacific #1
Harmon - Southern Pacific #2
Harmon Cyberscan 2000 - Standard Voice
Harmon Cyberscan 2000 - Canadian Voice
Progress Rail/GE Transporation Systems

The well known voice of Randy Goyer can be heard on MicroHBD & Micro Talker units all across North America. Little has changed with the audio of these units since their debut by GE Transportation Systems in the early 2000s, although the units have undergone many internal upgrades.

For the trained ear, you may be able to discern early GE Micro Talkers from more contemporary products. You can hear an ever so slight pauses between the word "track" and the track number, as well as between the letters in "CSX." Additionally, these units say "axles" while MicroHBD units say "axle" (singular). Unfortunately, newer Micro Talkers have no discernable difference in voice and can only be identified by their functionality as found in an employee timetable.

Norfolk Southern often utilizes Progress Rail Micro Talkers in conjunction with their Stress State Detectors - these are easily identified, as they generally say "NS" instead of "Norfolk Southern" and "MP" instead of "Milepost." However, NS Micro Talkers used in other roles (such as a dragging equipment detector) use identical speech patterns as their MicroHBD units.

As with previous models, CN has opted to use a custom Canadian male voice for their defect detectors. The 1000 hz tone at the beginning is a clue as to what unit is in the bungalow.

GE Micro Talker - Early
Progress Rail MicroHBD - Current
Progress Rail Micro Talker - NS SSD
Progress Rail MicroHBD - Canadian Voice
Servo Corp.

Servo had a long history of defect detectors, although only the last few models were able to talk as-built: the 8909 & the 9000. The unmistakable voice is often referred to as the "Speak & Spell" model by railfans.

Union Pacific's Servo 9000 units utilized a female voice that is just as robotic-sounding as the male voice.

A notable variation are Canadian Pacific's fleet of System 9000 detectors, which included a custom Canadian male voice. Ontario Northland also utilized the System 9000 with the same custom voice.

Servo 8909
Servo 9000 - Standard Voice
Servo 9000 - Alternate Voice
Servo 9000 - Female Voice
Servo 9000 - Canadian Voice
Southern Technologies Corp.

Southern Technologies Corp. (STC) has 3 generations of hotbox detectors: the Sentry, the SmartScan NG, and the SmartScan NG². Non-heat detecting models included certain Sentry models (black casing, whereas heat detecting models had a blue casing), the Small Talk, and the iCUBE.

The Sentry and the SmartScan NG both use the same voice (that of an STC employee named Paul), which can make it easy to confuse the two. Early Sentry 2058s has a slightly muffled sound, a quicker pace, and the tendency to say "dot" instead of "point" for the milepost location. The Sentry 2058 commonly featured a female voice as well (that of STC employee named Linda), as heard commonly on Southern Pacific and Union Pacific. Later Sentry 2100s, common to BN/BNSF, sound virtually identical to the SmartScan NG. As of 2024, very few Sentry units remain in active service, and those that do are exclusively used on shortlines & regionals.

STC's Small Talk was a very simplistic, non-heat detecting unit. NS purchased many of these units to replace its aging ex-Conrail Parker DED 1GG units. They can be identified by their hybrid voice, which utilized the Sentry 2058-style voice for the railroad name & the word "milepost," while the rest of the message utilized the SmartScan NG-style voice. They also say "point" as opposed to "dot" for the milepost location. The Small Talk started production in the 1990s and was replaced by the iCube.

The SmartScan NG was introduced in 2004 as the successor to the Sentry 2100, so knowing which railroads utilized what units and the years they were in service is crucial to knowing what was actually in the bungalow. With that said, the SmartScan NG was a much more widely used model than the Sentry 2100. As of 2024, SmartScan NG units are being replaced en mass with SmartScan NG²s, but there are still a decent number out there.

In lieu of the SmartScan NG, Union Pacific opted to utilize a custom model from STC: the SmartScan IS. The SmartScan IS also utilizes Linda's voice, making it difficult to tell which model a detector is simply by its voice alone.

STC's iCUBE model is a small, non-heat detecting unit used for dragging equipment, slide fences, WILD detectors, etc. (similar in function to Progress Rail's Micro Talker). This model was introduced in the 2010s as a replacement for the Small Talk, and utilized the same voice as the SmartScan NG. Contemporary units use the same computer synthesized voice of the SmartScan NG².

The SmartScan NG² has a very distinctive computer-synthesized male voice and began appearing around 2017. Most railroads utilize a voice known as ‘Ryan’, while Canadian Pacific utilizes a bilingual voice known as ‘Matthew.’ While Union Pacific has opted to use this off-the-shelf unit this time around, they have chosen to utilize a computer-synthesized female voice (named ‘Linda’, but clearly different from the STC employee Linda's voice).

STC Sentry 2058 - Male Voice
STC Sentry 2058 - Female Voice
STC Sentry 2100
STC Small Talk
STC SmartScan NG
STC SmartScan IS
STC SmartScan NG² - Male Voice 'Ryan'
STC SmartScan NG² - Male Voice 'Matthew'
STC SmartScan NG² - Female Voice 'Linda'
Spirit Solutions

Spirit Solutions was a short-lived manufacturer of thermal imaging-based defect detectors. Only one such installation is known (PT 241.0 on NS' Pittsburgh Line), which was subsequently replaced.

The voice heard here is that of Microsoft Sam, the default voice generator found on Windows 2000 and Windows XP. It is a common voice used by smaller manufacturers, so further verification is needed beyond the voice itself to identify what is actually in the signal bungalow.

Spirit Solutions MidNight Ridir

Detectors that we have not yet identified. Many are dragging equipment detectors, as they are simpler unit that are easy to build in-house, or were short-lived products from various companies.


  • Boston & Maine DED: Older model from at least the early 1990s, if not the 1980s.
  • Buckingham Branch DED: Newer model, possibly in-house. It uses the Microsoft Sam voice common to other oddball detectors (such as the Spirit Solutions MidNight Ridir).
  • Canadian National DED: No additional information available.
  • Conrail HBD: A retrofitted Servo detector that did not have factory talker capabilities. Used cassettes to play back audio. Devtronics' Mini-Analyzer was used for this purpose by other railroads, unknown if this is what is being heard here however.
  • Reading & Northern DED - Male Voice: Newer model, possibly in-house.
  • Reading & Northern DED - Female Voice: Another newer model, again possibly in-house.
Boston & Maine DED
Buckingham Branch DED
Canadian National DED
Conrail HBD
Reading & Northern DED - Male Voice
Reading & Northern DED - Female Voice

Zukinut's ZEPIC-DE dragging equipment detector is a discontinued model. Zukinut does, however, still produce derailment detectors.

Zukinut ZEPIC-DE