A sonic logo lasts two or three seconds. In that time it is supposed to do what a visual logo does on a page: identify the brand and bring some of its meaning to mind. Practitioners have written about the design of such sounds for two decades (Jackson, 2003), and academic interest has followed, though a review of the field found it fragmented and short of consumer-level evidence (Gustafsson, 2015). One reason is that the outcome is awkward to measure. A listener may hum a jingle without being able to name the advertiser, or feel that a chime is familiar without knowing why.

Standard practice relies on two questions. Unaided recall asks which brands' sounds the respondent can think of. Aided recognition plays a clip and asks whose it is. Both correspond to the components of brand awareness in Keller's (1993) model, and both are explicit: they require deliberate retrieval and a verbal report. Memory research has long distinguished this from implicit memory, in which earlier exposure affects later performance without conscious recollection (Schacter, 1987). Sound is a plausible carrier of the second kind. In a well-known field experiment, the nationality of background music in a shop shifted which wines were bought, while shoppers appeared unaware of any influence (North et al., 1999).

This article proposes a protocol for measuring sonic branding recall that adds two elements to the standard questions: implicit association tasks that use sound clips as stimuli, and a listening diary that records encounters with brand sounds in daily life. The protocol is a methodological proposal. No data are reported and the procedure has not been validated here.

Each of the three sources answers a different question and has a characteristic weakness. Explicit recall shows what a listener can retrieve and name, but it depends on motivation, on verbal labels and on the cues the questionnaire happens to offer. Early work on jingles found that music helps people remember advertising slogans mainly when other retrieval cues are scarce (Yalch, 1991), which implies that the wording of a recall question can itself change the result. Explicit measures also say nothing about whether the sound has acquired the meanings the brand intended.

The Implicit Association Test was devised to measure the strength of associations between concepts from the speed of sorting decisions, without asking the respondent to report them (Greenwald et al., 1998). It has been applied to brands, where it has predicted preference and behaviour and added to what explicit ratings explained (Maison et al., 2004; Brunel et al., 2004). Its stimuli are usually words or pictures. Nothing in its logic requires this, and short sounds can in principle be sorted in the same way.

Neither kind of test shows how often, where or in what state of attention the listener has met the sound. Diary methods are designed for exactly that. They collect brief reports close to the events they describe and so reduce reliance on memory over long intervals (Bolger et al., 2003; Shiffman et al., 2008). Experience sampling has been used to describe how people use music in ordinary life (Sloboda et al., 2001), and the same approach can be pointed at brand sounds. Figure 1 sets out the three strands and the measures within each.

The protocol consists of a first test session, a diary period and a second test session. Its six steps are described below.

A full application is demanding, and commercial users may wish to take parts of it. The linkage task and the explicit questions can be run in a single online session of about twenty minutes and would already show whether a sound that scores poorly on recognition is nonetheless tied to the brand. The diary adds cost and should be reserved for questions about media planning, such as whether exposure in audio-only settings builds the association as well as exposure with pictures does. The number of respondents should be fixed by a power analysis based on the reliability of the tasks observed in piloting, not by convention. Respondents must be told that their listening habits are being recorded, and diary data should be stored apart from identifying details.

The protocol has not been tried. Its least certain element is the use of sounds as stimuli in association tasks. A sound unfolds in time, so the moment at which it can be identified varies from clip to clip, and that variation enters the response latencies on which the score depends. Piloting would have to show that auditory versions reach acceptable internal consistency and stability over time before any substantive use.

The wider debate about the test also applies. Its scores are relative, its reliability is lower than that of most questionnaires, and reviewers disagree about how well it predicts behaviour: one meta-analysis reports useful predictive validity across domains (Greenwald et al., 2009), while another, restricted to studies of discrimination, finds weak prediction (Oswald et al., 2013). An association between a sound and a brand is not evidence that the sound sells anything. Diaries bring their own problems. Keeping one draws attention to brand sounds and may change what is noticed afterwards, so the second session measures respondents who have been sensitised. A comparison group that completes both sessions without a diary would show the size of that effect.

Recognition questions alone give a narrow view of what a sonic logo has achieved. The protocol proposed here sets beside them an implicit measure of how firmly the sound is tied to the brand, an implicit measure of what the sound has come to mean, and a diary record of where and how it was heard. The three are meant to be read together, with disagreement between them treated as information. The auditory association tasks in particular are untested, and establishing their reliability is the first piece of work that anyone adopting the protocol should undertake.

To be declared by the author(s) before publication.

To be declared by the author(s) before publication.