# Voice Maps as a Tool for Understanding and Dealing with Variability in the Voice
## 4 Discussion and Conclusions
### Concluding Remarks  
Voice mapping is not in itself a kind of measurement. It is a paradigm for the coordinated acquisition of data and visualization of multiple concurrent measurements, in which the momentary SPL and \(f_{\circ}\) are continuously accounted for, much more data is collected for every individual, and the co-variation of different metrics can be made explicit. Thus, voice mapping offers opportunities for accounting for many of the sources of variation in the voice, thereby improving on more conventional data collection paradigms. We hope to have shown that the potential of voice mapping goes well beyond that of the legacy voice range profile, including:  
* offering the clinician, researcher, and informant a richer yet equally compact presentation of vocal status, in real time;
* mapping even small or local changes across interventions, while accounting for their trends over SPL and \(f_{\circ}\), even if those trends are non-linear and personal;
* finding the metric values that are the most representative of the individual's vocal status, in ecologically valid tasks;
* assessing the range of variation in a metric, in a given task;
* assessing the sensitivity of a metric to changes in SPL and \(f_{\circ}\). Although these are all improvements, it is clear that a number of tasks remain if we are to make substantial progress towards the long-term goal of improving the general reliability of non-invasive objective voice measurements. Some of these tasks are practical,others theoretical, and they will iteratively inform each other, so concurrent progress will be needed on all fronts. A list of tasks for the next few years could read as follows:  
* Testing statistical clustering of several metrics, applied in real time so as to automatically and quantitatively identify regions of different types of phonation [25]. This should facilitate making the connection to perceptual assessment and ultimately to a deeper functional assessment of voices. Even though we strive for objective rather than subjective assessment, a grounding in current clinical perceptual methodology is very important both for understanding and for uptake;
* Identifying compact sets of voice metrics that are especially relevant for assessing voice signals in the context of particular vocal pathologies and/or training objectives, in other words, what to measure in which situation;
* Outreach: voice scientists presenting and discussing voice mapping with clinicians and voice pedagogues in workshops and courses, and learning more about their priorities [54];
* In-the-field applications: Solving the technical problem of SPL calibration in poorly controlled situations such as telehealth, which could increase the influx of research data; implementations for mobile devices;
* Performing pre-post intervention studies, so as to gain experience with clinically or pedagogically relevant effect sizes, for the interpretation of difference maps;
* Making quantitative voice assessment more functionally oriented and clinically relevant by mapping the location and extent of phonation type regions across the voice field, rather than by assessing voice quality using statistically derived cut-off values for metrics and composite indexes. Most importantly, voice mapping reveals things about the voice that we did not already know. This is our incentive to continue the pursuit. Each new observation is an opportunity for questioning our models, and for making more complete models that offer better explanations. Voice mapping provides a fertile ground for making new observations, as well as for placing both the expected and the unexpected into a frame of reference that can be shared and built upon. Conceptualization and methodology, P.P. and S.T. ; software, S.T. ; writing --original draft preparation, S.T. and P.P. ; writing--review and editing, S.T. and P.P. ; visualization, S.T. All authors have read and agreed to the published version of the manuscript. The writing of this overview article received no external funding. Not applicable.