The Inter-American Court and Commission of Human Rights, following the approach in key international human rights texts, have emphasized the importance of procedural rights in the protection of indigenous rights to territory and to cultural identity. In particular, the Court and Commission have focused on rights to consultation in a range of cases in which indigenous peoples have challenged mining, logging and other extractive activities on their territories. Consultation processes are often expected to serve a wide range of purposes in the protection of indigenous rights and interests in territory. Consultation is a means of informing a community about a project, but also a process through which an agreement can be reached between the community and the State about the use of territory or the sharing of benefits. In this article, I focus on consultation's role as part of the impact assessment process. In determining the impact that a project might have on indigenous territory, the Court and Commission have found that the State must assess both the environmental and cultural impacts of a plan or activity. Consultation is a necessary part of the identification of the impacts of an activity and ensuring that the State has all the necessary information prior to making decisions to grant concessions over indigenous territory. However, the Court and Commission's interpretation of indigenous testimony in consultation processes could undermine the role of such testimony in the assessment of environmental impacts, and might silence indigenous participants rather than ensure their meaningful participation. With reference to the idea of illocutionary silencing, taken from feminist speech act theory, I argue that the Court and Commission have interpreted indigenous testimony about the environment as being claims about the cultural impacts of disputed activities or plans, and not as claims about the environmental impacts. In other words, when indigenous community members have offered descriptions of their territories and surrounding environments, such testimony has been treated not as descriptions of the environment but as reports of cultural beliefs and practices. As a result, indigenous input in regard to the environmental impacts of a project or plan can be overlooked. In this article I argue that this failure to recognize indigenous accounts of the environment means that these communities are silenced through the consultation process and denied the opportunity to be informed about all relevant impacts.