Information on data and consultants
Additionally to studying the literature, we conducted research to find accurate information on the number of deaf, deafblind, hard of hearing, and other signing people in the Netherlands. As mentioned above, some numbers were easier to come by than others: the number of sign language interpreters described above, for example, is based on the number of registered interpreters. As for the number of deaf(blind) people and/or signing people, the situation is more complex. It has certainly struck me how much variation I found in the numbers provided by others. Between 2016 to 2020, we consulted the following literature: Balder et al. (2000), Breed & Swaans-Joha (1986), Cokart et al. (2019), Commissie Erkenning Nederlandse Gebarentaal (1997), Drullman (2019), van den Dungen (1999, in Radstake 2002), KNAW (2018), Prawiro-Atmodjo et al. (2016), Tijsseling (2009), and Wheatley & Pabsch (2012). Additionally, we looked for numbers on the website of the Ministry of Health (www.volksgezondheidenzorg.info), on the website about the national neonatal hearing screening (www.pns.nl), the website from national associations such as Dovenschap (www.dovenschap.nl) and Hoormij (www.hoorwijzer.nl), and a website with information about cochlear implantation (ww.opciweb.nl). We consider the information of Prawiro-Atmodjo et al. (2016) on the number of early onset deaf people reliable, but still wanted to try to find more recent and precise numbers. Since claims differed from an estimation of about 7,500 early onset deaf people in the Netherlands in 1997 (Commissie meer dan een Gebaar 1997) to more concrete numbers, such as that 3 in 1,000 children are born with a hearing loss, and 1 in 1,000 children with a severe hearing loss (Tijsseling 2009), we sometimes had to calculate numbers ourselves, considering various percentages, different definitions, and a growing national population. After also reading Johnston’s papers (see Footnote 30), and discussing with Onno Crasborn (Professor of Sign Language at the Radboud University Nijmegen, p.c. July 2019), we came to the previously described conclusion that the number of deaf sign language users cannot be more than 10,000 people.